Publisher: Jitendar P Vij Publishing Director: Tarun Duneja Editor: Richa Saxena Cover Design: Seema Dogra Textbook of Medical Biochemistry First Edition. EIGHTH EDITION Textbook of V* MEDICAL BIOCHEMISTRY MN Chatterjea Rana Shinde JAYPEE Textbook of Medical Biochemistry Textbook of Medical. It excels time! Time for reviewing Textbook Of Medical Biochemistry By Chatterjee And Shinde. Pdf, as best seller book in this wolrd. Don't have.

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Textbook of Medical Biochemistry (8th Ed.) - Ebook download as PDF File .pdf), Text File .txt) or read book online. MN chatterjee Biochemistry. “Today's Biochemistry is Tomorrow's Medicine” rightly said by many is truly justified by “Dr and Dr Rana Shinde in their Textbook of Medical Biochemistry”. medical biochemistry by m pdf. Textbook of medical Biochemistry pdf by Mn Chatterjea pdf: Textbook of medical physiology is written by Mn Chatterjea and.

At low concentrations, the process is carrier-mediated. At higher concentrations, absorption also occurs via passive diffusion. Active transport is greatest in the jejunum and ileum, but it can be inhibited by alcohol consumption or by folate deficiency.

A specific binding protein called thiamine-binding protein TBP has been identified in rat serum and is believed to be a hormone-regulated carrier protein important for tissue distribution of thiamine. ThMP and free unphosphorylated thiamine is present in plasma, milk, cerebrospinal fluid , and, it is presumed, all extracellular fluid.

Unlike the highly phosphorylated forms of thiamine, ThMP and free thiamine are capable of crossing cell membranes. Calcium and Magnesium have been shown to affect the distribution of thiamine in the body and Magnesium deficiency has been shown to aggravate thiamine deficiency.

The best-characterized form is thiamine pyrophosphate TPP , a coenzyme in the catabolism of sugars and amino acids.

Essentials of Medical Biochemistry

In yeast, TPP is also required in the first step of alcoholic fermentation. All organisms use thiamine, but it is made only in bacteria, fungi, and plants.

Longer survival was due not only to significant improvements in cerebral blood flow, but also to an increase in the level of glucose and ATP 44, 48— Other studies have shown that a G. Intravenous infusion of G. The active constituents of G. Furthermore, intravenous administration of a standardized G.

The constituents of G. The flavonoids, ginkgolides, and bilobalide have all been suggested, but it is possible that other constituents may be responsible. An extract of G. Bilobalide appeared to play a significant role in the antioedema effect 61, Oral or subcutaneous administration of an extract of G. Mice treated with a standardized extract of G. Vestibular and auditory effects Ginkgo biloba extract improved the sum of action potentials in the cochlea and acoustic nerve in cases of acoustically produced sound trauma in guinea-pigs 1, The mechanism reduced the metabolic damage to the cochlea.

Oral or parenteral administration of a standardized G. Improvement was due to the effects of the drug on capillary permeability and general microcirculation 1, Positive effects on vestibular compensation were observed after administration of G.

PAF is a potent inducer of platelet aggregation, neutrophil degranulation, and oxygen radical production leading to increased microvascular permeability and bronchoconstriction. Intravenous injections of PAF induced transient thrombocytopenia in guinea-pigs, which was accompanied by nonhistamine- dependent bronchospasm 69, Ginkgolide B has been shown to be a potent inhibitor of PAF-induced thrombocytopenia and bronchoconstriction 71, Clinical pharmacology Cerebral insufficiency Cerebral insufficiency is an inexact term to describe a collection of symptoms associated with dementia 21, In dementia owing to degeneration with neuronal loss and impaired neurotransmission, decline of intellectual function is associated with disturbances in the supply of oxygen and glucose.

In clinical studies G. Several mechanisms of action of G. Treatment of humans with G. A critical review of 40 published clinical trials up to the end of using an orally administered G.

Almost all trials reported at least a partially positive response at dosages of —mg a day standardized extract and treatment for at least 4—6 weeks 21, In a comparison of G. A direct comparison of mg of G. A meta-analysis of 11 placebo-controlled, randomized double-blind studies in elderly patients given G. Significant differences were found for all analysed single symptoms, indicating the superiority of the drug in comparison with the placebo.

Analysis of the total score of clinical symptoms indicated that seven studies confirmed the effectiveness of G. Peripheral arterial occlusive disease The effectiveness of G.

Sixty patients with peripheral arterial occlusive disease in Fontaine stage IIb who were treated with the drug —mg for 24 weeks and underwent physical training also clearly increased their walking distance Out of 15 controlled trials up to the end of only two 23, 24 were of acceptable quality 22— The results of both studies were positive and showed an increase in walking distance in patients with intermittent claudication after 6 months 23 , and an improvement of pain at rest in patients treated with mg of G.

After meta-analysis of five placebo-controlled clinical trials up to the end of of G. Vertigo and tinnitus Ginkgo biloba extracts have been used clinically in the treatment of inner ear disorders such as hearing loss, vertigo, and tinnitus. In a placebo-controlled, double-blind study of 68 patients with vertiginous syndrome of recent onset, treatment with G. The results of clinical studies on the treatment of tinnitus have been contradictory.

At least six clinical studies have assessed the effectiveness of G. Three studies reported positive results 86, 87, One multicentre, randomized, double-blind, month study of patients with tinnitus showed that all patients improved, irrespective of the prognostic factor, when treated with G.

Three other clinical trials reported negative outcomes 89— Statistical analysis of an open study 80 patients without placebo, coupled with a double-blind, placebo-controlled part 21 patients , demonstrated that a concentrated G. Contraindications Hypersensitivity to G. Warnings Precautions Carcinogenesis, mutagenesis, impairment of fertility Investigations with G. Pregnancy: non-teratogenic effects The safety of Folium Ginkgo for use during pregnancy has not been established.

Nursing mothers Excretion of Folium Ginkgo into breast milk and its effects on the newborn have not been established. Other precautions No information is available concerning general precautions or drug interactions, drug and laboratory test interactions, teratogenic effects on pregnancy, or paediatric use.

Adverse reactions Headaches, gastrointestinal disturbances, and allergic skin reactions are possible adverse effects Posology Dried extract as described in Dosage forms , —mg daily in 2 or 3 divided doses 2 ; 40 mg extract is equivalent to 1. Fluid extract 1: 1 , 0.

References 1. DeFeudis FV. Ginkgo biloba extract egb : pharmacological activities and clinical applications. Paris, Elsevier, Editions Scientifiques, Hagers Handbuch der pharmazeutischen Praxis, Vol.

Berlin, Springer-Verlag, Squires R. Ginkgo biloba. Huh H, Staba EJ. The botany and chemistry of Ginkgo biloba L. Journal of herbs, spices and medicinal plants, , — Farnsworth NR, ed. Keys JD. Chinese herbs, their botany, chemistry and pharmacodynamics. Pharmacopoeia of the People's Republic of China English ed.

Guangzhou, Guangdong Science and Technology Press, Melzheimer V. Ginkgo biloba L. Pharmazie in unserer Zeit, , — Thin layer chromatography of bilobalide and ginkgolides A, B, C and J on sodium acetate impregnated silica gel. Phytochemical analysis, , — Journal of chromatography, , — Hasler A, Meier B. Determination of terpenes from Ginkgo biloba by GLC. Pharmacy and pharmacology letters, , — Quality control methods for medicinal plant materials. Geneva, World Health Organization, Deutsches Arzneibuch Methoden der Biologie.

Stuttgart, Deutscher Apotheker Verlag, European pharmacopoeia, 3rd ed. Strasbourg, Council of Europe, Sticher O. Biochemical, pharmaceutical and medical perspectives of Ginkgo preparations. Guidelines for predicting dietary intake of pesticide residues, 2nd rev. Quality of Ginkgo preparations. Planta medica, , — Van Beek TA et al. Determination of ginkgolides and bilobalide in Ginkgo biloba leaves and phytochemicals.

Hasler A et al. The three basic science subjects make a plinth for the house of medicine. A sound and comprehensive learning of biochemistry will help a medical student understand medicine and pathology more clearly. A large number of books on biochemistry for medical students are available in the market—both international and Indian. Many of the international books are voluminous and too difficult for our students of medicine to handle and comprehend. The Textbook of Medical Biochemistry for the medical students is the outcome of the joint efforts of a medical and a nonmedical biochemist, who possess considerable experience in teaching biochemistry to undergraduate and postgraduate medical students of Indian universities.

We have tried our utmost to ensure that the language used is lucid and simple, makes an easy-reading, and the text provides an intelligent and comprehensive study. At the same time, we have attempted to maintain a high standard after incorporating the recent developments and concepts.

Though the book is primarily meant for the first professional MBBS students, certain chapters have been dealt with in greater detail to meet the requirements of postgraduates, viz. It meets the requirements of students of medical, dental science, agricultural science, home science, and others who have to take a basic course in biochemistry.

The text of the book is spread over 40 chapters and special mention has been made to introduce to the reader some recent topics such as cyclic nucleotides—cyclic AMP and cyclic GMP, prostaglandins, prostacyclins, thromboxanes and leukotrienes, immunoglobulins, recombinant DNA technology, clinical significance of enzymes and isoenzymes, radioisotopes and their clinical and therapeutic uses, etc.

The text of each chapter has been written keeping in view the objectives so that students can make a self-study. Though this is unavoidable to some extent for proper understanding of the subject, we have tried to restrict the chemical formulae to the minimum and used them to explain certain reactions.

It will be seen that there is repetition of some questions, but the framing of the question and language is different. We have also tried to give some 15 to 30 MCQs with answers at the end in each chapter which may be useful for the medical students for their homework.

While writing the chapters and compiling the questions, we have consulted syllabi of several Indian universities to cover all the topics prescribed for undergraduate and postgraduate medical students. We have included a large number of tables and comparative discussions wherever possible to meet the needs of the students.

Our aim has been to provide a comprehensive, self-contained textbook of biochemistry to effectively satisfy the curricular requirements of medical students of Indian universities. In addition, our main target has been to make the book clinically-oriented. We have given the clinical significance and biomedical importance wherever it is applicable.

Biochemical aspects of certain pathological conditions, specially those due to abnormal metabolism, have been discussed in detail. We earnestly hope that the book will be of help to both the undergraduate and postgraduate medical students and their teachers. No one can be perfect, and there could have been some flaws or shortcomings in the book. We will welcome constructive criticism and comments, if any, along with fruitful suggestions to improve the text in its future editions.

In writing a textbook of this nature, one has to take help from others and this book is no exception. We are highly indebted to our colleagues and friends, and other authors whom we have consulted in compiling this book. MN Chatterjea Rana Shinde. Cell Biology 1. Cell and Cell Organelles: Chemistry and Functions Biological Membranes: Structure and Function Transport System Chemistry of Biomolecules 3.

Chemistry of Carbohydrates Chemistry of Lipids Prostaglandins—Chemistry and Functions Chemistry of Proteins and Amino Acids Plasma Proteins—Chemistry and Functions Immunoglobulins—Chemistry and Functions Hybridoma Chemistry of Enzymes Biological Oxidation Chemistry of Haemoglobin and Haemoglobinopathies Chemistry of Respiration and Free Radicals Molecular Biology Chemistry of Nucleotides Metabolism of Purines and Pyrimidines Human Genome Project Functional Genomics Gene Therapy Biochemistry of Cholera—Vibrio Toxins, Pathogenesis Metabolism Digestion and Absorption of Carbohydrates Metabolism of Carbohydrates Digestion and Absorption of Lipids Metabolism of Lipids Digestion and Absorption of Proteins Metabolism of Proteins and Amino Acids Integration of Metabolism of Carbohydrates, Lipids and Proteins Metabolism in Starvation Porphyrins and Porphyrias Synthesis of Haem Haem Catabolism Metabolism of Minerals and Trace Elements Clinical Biochemistry Enzymes and Isoenzymes of Clinical Importance Renal Function Tests Liver Function Tests Gastric Function Tests Thyroid Function Tests Water and Electrolyte Balance and Imbalance Acid Base Balance and Imbalance Radioisotopes in Medicine Introduction to Biochemical Techniques.

Biochemistry of Cancer Miscellaneous Coffee and Cocoa Diet and Nutrition Biochemistry of Ageing Biochemistry of AIDS Principles and Biomedical Importance Environmental Biochemistry Thus cell is the fundamental unit of life. Eukaryotic Cells The eukaryotic cells Greek: Eu-true and karyon-nucleus include the protists. If cell dies. All animal tissues including human are also organised from collections of cells. Prokaryotic and eukaryotic cell. Their structure and functions.

All organisms are built from cells. Specific Objectives 1. Study the following cellular organelles: Prokaryotic cells 2. Eukaryotic cells 1. They are: To know importance of cell. Learn its structure and functions. Cells are larger in size Fig. Draw a diagram of an eukaryotic cell showing different cell organelles.

Prokaryotic Cells Typical prokaryotic cells Greek: Pro-before and karyonnucleus include the bacteria and cyanobacteria. Types of Cells In general two types of cells exist in nature. Modern cell theory can be divided into the following fundamental statements: Most studied prokaryotic cell is Escherichia coli E. Learn the essential differences of a prokaryotic cell and eukaryotic cell. Not well defined nucleus. Cytoplasm contains no cell organelles 8. Cytoskeleton—absent Golgi apparatus absent.

Enzymes of energy metabolism bound to membrane 9. No nuclei 7. Schematic representation of an eukaryotic cell with cell organelles radiant energy to chemical energy is the highly structural chloroplasts.

Lysosomes—absent Mitochondria absent. Essential differences between prokaryotic and eukaryotic cells Prokaryotic cell Eukaryotic cell 1. Essential differences of prokaryotic and eukaryotic cells are given in Table 1. Anaerobic or aerobic 5. Cell division usually by fission. Examples are bacteria. Single membrane. Several different types present Lipid bilayer membrane with proteins Aerobic Nucleus well defined. Ribosomes present free in cytoplasm 3.

Enzymes of energy metabolism are located in mitochondria Golgi apparatus present—flattened single membrane vesicles Lysosomes present—single membrane vesicle containing packets of hydrolytic enzymes Cell division—by mitosis Cytoskeleton—present RNA synthesised and processed in nucleus.

Storage granules with polysaccharides RNA and protein synthesis in same compartment Proteins synthesised in cytoplasm Examples: Mainly unicellular 1. DNA in the nucleus is coiled into a dense mass called chromatin. Some algae contain only one mitochondrion. Chemistry and Functions. Nucleoplasm of nucleus contain various enzymes such as DNA polymerases.

Transcription is the first step in the expression of genetic information and is the major metabolic activity of the nucleus. The outer membrane also contains many copies of the protein called Porin. They vary greatly in size. These complex structures control the movement of proteins and the nucleic acid ribonucleic acids RNAs across the nuclear envelope.

A double membrane structure called the nuclear envelope separates the nucleus from the cytosol. A typical mammalian mitochondrion has a diameter of 0. Mitochondria assume many different shapes under different metabolic conditions. The number of mitochondria in a cell varies dramatically. Structure and Functions The mitochondrion is bounded by two concentric membranes that have markedly different properties and biological functions. Mitochondrion is the power house of cell Figs 1.

Mitochondrial Membranes a Outer mitochondrial membrane: The outer mitochondrial membrane consists mostly of phospholipids and contains a considerable amount of cholesterol.

A mitochondrion—shows half split to show the inner membrane with cristae 5 2. Chief organelles and their functions are as follows: A second dense mass closely associated with the inner nuclear envelope is called nucleolus.

A mammalian liver cell contains from to mitochondria. Cell Organelles Eukaryotic cells contain many membrane-bound organelles that carryout specific cellular processes. These are embedded in the nuclear envelope.

The shape of mitochondrion is not static. It contains high proportion of the phospholipid cardiolipin. The matrix also contains several strands of circular DNA. The inner mitochondrial membrane is highly folded. The mitochondrion is not. Varying in shape. In the respiring state. Functional changes: It is now known that mitochondria undergo dramatic changes when they switch over from resting state to a respiring state.

The inner mitochondrial membrane is very rich in proteins and the ratio of lipid to proteins is only 0. Composition of matrix: The enzymes responsible for citric acid cycle and fatty acid oxidation are located in the matrix. Table 1. Enzymes of electron transport and oxidative phosphorylation are also located in different areas of this cell organelle. In contrast to outer membrane. The space between the outer and inner membranes is known as the intermembrane space.

The region enclosed by the inner membrane is known as the mitochondrial matrix. Since the outer membrane is freely permeable to small molecules.

These membranes and the aqueous channels they enclose are called cisternae. Further mitochondrial DNA can be damaged by free radicals. These substances enter the mitochondrion only through the mediation of specific transport proteins. The energy produced is trapped and stored as ATP.

These organelles are involved in protein synthesis. Endoplasmic reticulum ER: Eukaryotic cells are characterised by several membrane complexes that are interconnected by separate organelles. H2 reduced FAD produced in the reactions of glycolysis. They can be grouped as follows: Lysosomal Enzymes 1.

There are two kinds of endoplasmic reticulum ER: The lysosomal enzymes have an optimal pH around 5. Mean diameter is approximately 0.

Golgi complexes or Golgi apparatus: They are also called Dictyosomes. They do not have attached ribosomes. These include the enzymes responsible for the synthesis of sterol. It is interesting to note that those proteins with no signal or transit peptides regions are rejected by the Golgi apparatus without processing it further and remain as cytoplasmic protein.

Proteolytic enzymes 2. Recent evidence suggests strongly that the complex serves as a unique sorting device that receives newly synthesized proteins.

Lipid hydrolysing enzymes 4. The ER is usually closely associated with the Golgi complexes. Cytochrome P which participates in drug hydroxylation reside in the ER. Each eukaryotic cell contains a unique stack of smooth surfaced compartments or cisternae that make up the Golgi complex.

These proteins are inserted through the ER membrane into the lumen of the cisternae where they are modified and transported through the cell. Acid phosphatase is used as a marker enzyme for this organelle.

They are coated with ribosomes. The Golgi complex has a Proximal or Cis compartment. Lysosomes are cell organelles found in cells which contain packet of enzymes. Discovered and described for the first time as a new organelle by the Belgian Biochemist de Duve in Nucleic acid hydrolysing enzymes 3. They are surrounded by a lipoprotein membrane. Near the nucleus. The enzymes are active at postmortem autolysis.

Phospholipids PL and the enzymes involved in detoxification of drugs. Enzyme Groups Present in Lysosomes Essentially the enzymes about 30 to Smooth endoplasmic reticulum is involved: A number of important enzymes are associated with the endoplasmic reticulum of mammalian liver cells. These secretory vesicles move to and fuse with the plasma membrane where the contents may be expelled by a process called exocytosis.

Acid phosphatase Catalase. But when the membrane is ruptured. Lysosome word derived from Greek word Gree. Functions a Function of rough ER: Rough ER synthesises membrane lipids. Carbohydrate splitting enzymes 5. Functions i On the proximal or cis side.

Inherited disorders: A number of hereditary diseases involving the abnormal accumulation of complex lipids or polysaccharides in cells of the afflicted individual have now been traced to the absence of key acid hydrolases in the lysosomes of these individuals. Sequence of events in genesis of I-cell disease: I-Cell disease: I-cell disease is a rare condition in which lysosomes lack all of the normal lysosomal enzymes.

The lysosomes thus accumulate many different types of undegraded molecules forming inclusion bodies. These crystals when phagocytosed cause physical damage to lysosomes and release of enzymes producing inflammation and arthritis. Studies now support the idea that this compartment contains actually a complex network of fine structures called a microtubules. These subcellular respiratory organelles have no energy-coupled electron transport systems and are probably formed by budding from smooth endoplasmic reticulum ER.

In Gout: Urate crystals are deposited around joints. Allergic responses and arthritic conditions: Released enzymes from ruptured lysosomal membrane can hydrolyse external biopolymers substrates leading to tissue damage in many types of allergic responses and arthritic conditions.

The particles are approximately 0. Studies have shown that lysosomal enzymes from patients with I-cell disease lack a recognition marker. Hence these enzymes lack MannoseP the marker and are secreted into plasma leading to high plasma level.

Cultured cells from patients with I-cell disease found to be deficient in the enzyme GlcNAc phosphotransferase. Hence they can not be targeted to lysosomes. For many years. Peroxisomes are small organelles also called Microbodies. They are long unbranched slender cylindrical structures with an average diameter of about 25 nm. The structures are made primarily by the selfassembly of the heterodimer.

There is no specific structure for cytosol. DNA replication and transcription. Involved in protein synthesis. Power house of the cell. Maturation of synthesised proteins.

Biogenesis of proteins. Lipid metabolismFA synthesis. Function It is not yet clearly understood and established fully whether or not soluble enzymes are associated or clustered with these structures to form unstable multienzyme complexes.

Function These structures may be involved in the generation of forces for internal cell motion. Degradation of proteins carbohydrates.

Cytoplasm Cytosol This is the simplest structure of the cell. They are more slender cylinder like structures made up of the contractile protein actin.

They are linked to the inner face of the plasma membrane.

HMP shunt. A major role of cytosol is to support synthesis of proteins on the rough endoplasmic reticulum by supplying cofactors and energy.

Folium Ginkgo

Many metabolic reactions take place in cytosol where substrates and cofactors interact with various enzymes. They appear to be very fragile tubes that form a transient network in the cytosol.

It has a high protein contents. Organelles free sap is called as cytosol. TCA cycle. The actual physio- 9 chemical state of cytosol is poorly understood. They exist as 2 subunits and act as the site of protein synthesis. Cytosol also contains free ribosomes often in the polysome form. Table 2. It separates the cell contents from the outer environment.

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Plasma membranes have selective permeability that mediate the flow of molecules and ions into and out of the cell. The plasma membrane. Eukaryotic cells contain many internal membrane system that surround the cell organelles. Peripheral proteins: Passive or simple diffusion 2. Learn about special structural characteristics of red cell membrane 1. Active transport—Learn about uniport system.


Chemical Composition of the Membranes Membranes are composed of lipids. They also contain molecules at their surfaces that provide for cellular recognition and communication. Learn how lipid bilayer is formed B. Such a membrane barrier that separates cellular contents from the environment is an absolute necessity for life. Learn about nature of carbohydrates 4. Integral protein: Each internal membrane system is specialised to assist in the function of organelle it surrounds. All membrane carbohydrate is covalently attached to proteins or lipids.

Learn the chemical composition of the membrane—Lipids and its types. Study the fluid mosaic model structure of membrane and additional structures—Lipid rafts and caveolae C. Learn about i Phagocytosis ii Pinocytosis—Mechanism of receptor mediated absorptive pinocytosis 3. Exocytosis 2. Ankyrin and Band 4. The relative content of these components varies widely from one type of membrane to another.

Facilitated diffusion 3. Learn about proteins present and types: Oleic acid is the most abundant unsaturated fatty acid in animal membrane lipids. Cholesterol is another common component of the biomembranes of animals but not of plants and prokaryotes.

About 6 per cent of the membrane lipids of grey matter cells in the brain are gangliosides. Cephalin Phosphatidyl. The most common saturated fatty acid groups in membrane lipids in animals contain 16 to 18 carbon atoms.

They are another group of major components of biomembranes. Structure and Function. There are three types of sphingolipids sphingomyelin. About 50 per cent of the fatty acid groups are saturated. They comprise another group of lipids found in biological membranes specially in the tissues of nervous system.

Phosphatidylethanol amine cephalin. The other half of fatty acid molecules contain one or more double bonds.

Basic lipid structure—polar head and nonpolar tails 4. The nonpolar tails of most membrane lipids are long chain fatty acids attached to polar head groups.

Composition of different membranes: Content of lipid. Hence they are amphipathic Fig. Refer to chapter on Chemistry of Lipids for details of lipids. Sphingoserine myelin 12 20 20 25 19 17 7 3 2 0 4 6 12 2 4 3 5 7 Glycolipid 10 0 0 0 0 29 Types of Lipids Present in Biomembranes 1. Lipids are the basic structural components of cell membranes. Fatty acids: They are major components of most membrane lipids.

The degree of unsaturation determines the fluidity of the membranes. Approximately 5 per cent of the weight of cell membranes is carbohydrate. Early evidences for the model point to rapid and random redistribution of species—specific integral proteins in the plasma membrane of an interspecies hybrid cell formed by the artificially induced fusion of two different parent cells.

The phase changes. Within the plane of the membrane. This diffusion within the plane of the membrane is termed translational diffusion. These proteins can serve as receptors for hormones.

It has subsequently been shown that it is not only the integral proteins. Cholesterol helps to regulate fluidity of animal membranes.

It has amino acid residues and spans the lipid membrane. They can be removed without disrupting the membrane.

Transmembrane proteins: Some of the integral proteins span the whole breadth of the membrane and are called as transmembrane proteins. Fluid Mosaic Model of Membrane Structure The fluid mosaic model of membrane structure proposed by Singer and Nicholson in is now accepted widely. Integral membrane proteins also called intrinsic membrane proteins: These proteins are deeply embedded in the membrane.

Lipid bilayer. It can be quite rapid for a phospholipid molecule.

A lipid bilayer is about 6 nm across and this is so thin that it may be regarded as a two-dimensional fluid. It can be compared like icebergs floating in sea water Figs 2. The carbohydrate chains of many glycoproteins show structural variation from one molecule to another. Glycophorin is a major integral membrane glycoprotein of human erythrocytes. Thus portions of these proteins are in Van der Waals contact with the hydrophobic region of the membrane.

Carbohydrate chains are attached to the amino terminal portion outside the external surface. Glycerophospholipids and sphingolipids fulfil this criteria and hence can form bilayer. Occurs in cell membranes and in Lipoproteins. Peripheral membrane proteins also called extrinsic proteins: Lipid molecules in a bilayer are highly oriented Fig. Formation of Lipid Bilayer Membrane glycerophospholipids and sphingolipids spontaneously form bilayers.He prepared two isomeric forms of DGlucose by crystallisation under different conditions: They are: The important points in the text to be remembered by the students have been highlighted in bold and italicised prints.

European pharmacopoeia, 3rd ed. Thiamine is degraded by thermolabile thiaminases present in raw fish and shellfish [12]. Quality of Ginkgo preparations. The separation of optically active isomers from a racemic mixture is called resolution.

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