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Oraby's Illustrated Reviews of For Medical Students And Postgraduates By M.B.B. Ch, M.S. (Clinical Pathology) M.S. & MD (Medical Biochemistry) Professor of. جميع كتب دكتور سعيد عرابي pdf لمادة biochemistry الجزاء الاول http://www. yazik.info+Saeed+Oraby+Part+yazik.info الجزاء. Find oraby biochemistry part 1 book in our library for free trial. We provide copy of oraby biochemistry part 1 in digital format, so the resources that you find are.

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Said Oraby is the author of Oraby's Illustrated Reviews of Biochimistry ( avg rating, 12 ratings, 0 reviews, published ). Biochemistry Saeed Oraby Part 3 - Ebook download as PDF File .pdf), Text File ( .txt) or read book online. yhghgj. All about Oraby's illustrated reviews of biochemistry for medical students and postgraduates part.1 by Said Oraby. LibraryThing is a cataloging and social.

The rate of glycolysis is regulated by controlling of the three irreversible enzymes key enzymes. These enzymes catalyze what is called committed reactions of the pathway.

These enzymes nrc; glucokinase hexokinase , phosphofructokinase-! Hormonal rcKulntion; a Insulin: Stimulates synthesis of all key enzymes of glycolysis.

It is secreted after meal in response to high blood glucose level. Inltibits the activity of all key enzymes of glycolysis. It is secreted in response to low blood glucose level. Energy regulation: Substrate regulation: Fructose z,6 bispbosphate: It also inhibits gluconeogenesis by inhibiting fructose 1,6 bisphosphatase enzyme. Glucose n Insulin - - - - - -.

PFK-2 present mainly in liver bas bi-functional role: This reaction is stimulated after meal by fructosephosphate and insulin. This reaction is stimulated during fasting by glucagon hormone. Oraby's Illustrated reviews of biochemistry 32 ,! Differences between aerobic and anaerobic glycolysis: Substrate level phosphorylation in glycolysis: In glycolysis there are 2 examples: Importance of lactate production in anaerobic glycolysis: In absence of oxygen, lactate is the end product of glycolysis: Glucose -.

Pyruvate -. Lactatel 2. Carbohydrate metabolism 33 3. Special features of glycolysis in RBCs: Mature RBCs contain no mitochondria, thus: Glucose uptake by RBCs is independent on insulin hormone. Reduction of met-hemoglobin: Met-hemoglobin binds oxygen irreversibly. This reaction is catalyzed by cytochrome b 5 -met-haemoglobin reductase system cyt b 5: NAf H.

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Rapoport-Luebering cycle or 2,3 bisphosphoglycerate cycle. In the erythrocytes of many mammalian species the reaction! Pyruvate L. Glycernldhydephosphate is oxidized by glyceraldhydep dehydrogenase enzyme. This enzyme contains -SH group in its active center: Reversibility of glycolysis: Reversible reaction means that the same enzyme can catalyze the reaction in both directions. All reactions of glycolysis -except 3- are reversible. Carbohydrate metabolism 35 2. The 3 irreversible reactions those arc catalyzed by kinase enzymes are: During fasting, glycolysis is reversed for synthesis of glucose from non-carbohydrate sources as lactate.

This mechanism is called: Comparison between glucokinase and hexokinase enzymes: Glucokinase Hexokinase 1. Site Liver only All tissue cells 2. Affinity to Low affinity high km High affinity low km glucose i. Substrate Glucose only Glucose, galactose and fructose 4. Effect of Induces synthesis of No effect insulin glucokinase s.

Effect of No effect Allosterically inhibits glucose hexokinase phosphate 6. Function Acts in liver after meals. This leads to continuous supply of glucose for the tissues even in the presence of low blood glucose concentration.

Lactate dehydrogenase: It is an enzyme which catalyzes the reaction: It has 5 isoenzymes: Medical importance: Estimation of the activity of lactate dehydrogenase enzyme in plasma helps the diagnosis of heart and liver diseases: Elevated in some heart diseases e.

Elevated in some liver diseases as acute viral hepatitis. Oraby's illustrated reviews of biochemistry 36 P. In vitro inhibition of glycolysis: IGtyceroldhyde- 3- p Inhibits enolase enzyme. Clinical laboratories use fluoride to inhibit glycolysis by adding it to the blood before measuring blood glucose.

This is conversion of glucose into ethanol by yeast enzymes.

Pyruvate is formed by the same series of reactions of glycolysis. Then pyruvate is converted into acetaldehyde, then ethanol as follows: Thus the end product of fermentation is CO: Pyruvate decarboxylase! Sources and fate of lactate: From glycolysis especially in RBCs due to absence of mitochondria and muscle during exercises due to oxygen lack.

Glucose may diffuse back to the blood, then to red cells or muscles to be used for production of energy. This cycle is called: Lactic acid cycle or Cori cycle.

Definition of Cori cycle: It is the conversion of glucose into lactate in peripheral tissues, followed by conversion of lactate into glucose in liver. Carbohydrate metabolism 37 b Conversion into pyruvate: Liver Glucose t -! Clinical aspects of glycolysis: There a r e many di seases associated with impair ed g lyco lysis. Th ey includ e: Pyruvate kinase deficiency. Hexokinase d eficiency.

Lactic acidosis. Pyruvate kinase PK deficiency: Oraby's Illustrated reviews of biochemistry 38 2. Hexokinase deficiency: It leads to hemolytic anemia due to decrease ATP production. The mechanism is similar to that of PK deficiency.

Lactic acidosis: I It is the lowered blood pH and bicarbonate levels due to increased blood lactate above normal level. Lactic acidosis ,. It results from increased formation or decreased utilization of lactate. I Increased formation of lactate as in severe muscular exercises. Mitochondrial pathway for glucose oxidation: Complete oxidation of glucose occurs in both cytosol glycolysis and mitochondria Krebs' cycle.

In the presence of 02, pyruvate the end product of glycolysis passes by special pyruvate transporter into mitochondria which proceeds as follows: Pyruvate dehydrogenase PDH complex: These subunits are: Carbohydrate metabolism 39 b This enzyme needs 5 coenzymes all are vitamin B complex derivatives: PDH is located within the mitochondrial matrix. This produces 3 ATP molecules through respiratory chain phosphorylation.

Regulation of oxidative decarboxylation CPDHl: Phosphorylated inactive and dephosphorylated active. Summary of regulation: In vitro inhibition of PDH: Carbohydrate metabolism 41 3. Fumarate I H It ends by oxaloacetate 4 carbons. Energy production.. Energy 0-,. Pyruvate oxidation -. Acetyl CoA.. Oxidative decarboxylation of a-ketoglutarate to succinyl Co A: It is similar to the conversion of pyruvate to acetyl CoA.

Functions significance of TCA: TCA cycle is amphibolic i. Oxidation of carbohydrate, lipids and proteins. Anabolic functions: Formation of: TCA is the final common pathway for oxidation of carbohydrates, fats and proteins amino acids. Succinyl CoA ,. Nota that acetyl CoA Is producad In inltochondrla.

The Inner mltoc. To overcome this Impermeability, acetyl CoA combines with oxaloacetata to form citrate. Oxaloacetate Gluconeogenesis Glucose. Fatty acids. Carbamoyl phosphate ,. Urea and pyrimidine. Methyl malonyl CoA. Intermediate of citric acid cycle. Carbohydrate metabolism 45 7.

In vitro inhibition of TCA cycle: Regulation of citric acid cycle: TCA is regulated through the key enzymes citrate synthase, isocitrate dehydrogenase and a-ketoglutarate dehydrogenase and the availability of Oa: Long chain.

Oraby's illustrated reviews of biochemistry 46 b Isocitrate dehydrogenase and a-ketoglutarate dehydrogenase: Citric acid cycle needs oxygen to proceed i. Sources and fate of oxaloacetate: Final step in TCA cycle.

See protein metabolism. By pyruvate carboxylase and biotin see cu. Citrate Al:: I Formation of citrate: By citrate synthase first step in TCA cycle. Carbohydrate metabolism 47 Energy production at substrate level in glucose oxidation: If this energy is captured in phosphate or sulfate bonds, it will produce high-energy compounds. Pasteur effect: It is an alternative pathway for glucose oxidation where: ATP energy is neither produced nor utilized.

Oraby's Illustrated reviews of biochemistry 48 b In many tissues: It supplies pentoses for synthesis of nucleotides. Reactions steps: This pathway occurs in two phases; oxidative and non-oxidative: Oxidative irreversible phase: Non-oxidative reversible phase: Where the 3 molecules of ribulose-s-phosphate are interacted and converted into 2 molecules of glucosephosphate and one molecule of glyceraldhydephosphate.

Functions of pentose phosphate pathway: Production ofpentons: FA , cholesterol.. Production of pentoses: It is important for: Reduction of lutathlone: Hydroxylation of aromatic and aliphatic compounds: This is the major pathway. S Superoxide is then converted into H 2 0 2 by superoxide dismutase enzyme. Regulation of Pentose phosphate pathway: Glucosephosphate dehydrogenase is the key enzyme of pentose phosphate pathway. Differences between pentose phosphate pathway ppp and glycolysis: Pentose phosphate pathway in skeletal muscles: Skeletal muscles are poor in glucosephosphate dehydrogenase enzyme, but they contain transketolase and transaldolase enzymes.

Skeletal muscles ohtain their pentose requirement by reversible reactions of pentose phosphate pathway, using fructose phosphate and glyceraldehydep and the enzymes transketolase and transaldolase. Defects of pentose phosphate pathway: Carbohydrate metabolism 53 2. These toxic compounds increase the red cell membrane fragility.

Signs and symptoms of favism: Oraby's Illustrated reviews of biochemistry 54 1 Special food as fava beans. Uronic acid pathway: It is a minor pathway, in which glucose is converted into glucuronic acid.

Location of the pathway: Mainly liver. Functions importance of uronic acid pathway: This pathway produces glucuronic acid, which is important for: Synthesis of substrates: Conjugation reactions: UDP-glucuronic acid is used for conjugation with many body compounds to make them more soluble before excretion e.

Detoxification reactions: UDP-glucuronic acid is used for conjugation with toxic compounds to make them less toxic e. Fate of glucuronic acid see diagram: It is benign rare hereditary disease due to failure of conversion of L-xylulose into D-xylulose due to deficiency of L-xylulose reductase. L-xylulose will accumulate and be excreted in urine. Subjects excrete 1 to 4 grams of L-xylulose in the urine each day. Structure of glycogen: Glycogen is homopolysaccharide formed of branched a D glp. The main glycosidic bond is alinkage.

Only at the branGhing point, the chain is attached by a linkage. Each branch is made of glucose units.

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JcoSidlc 'lj. Location of glycogen: Glycogen is present mainly in cytosol of liver and muscles. Liver glycogen is about grams about 6 96 of liver weight.

Muscle glycogen is about grams about 1 96 of total muscles weight. Functions of glycogen: Liver glycogen: It maintains normal blood glucose concentration especially during the early stage of fast between meals. After hours fasting, liver glycogen is depleted. Muscle glycogen: It acts as a source LocaUon and funcUon of liver and muscle glycogen. Synthesis of glycogen glycogenesis: It is the formation of glycogen in liver and muscles.

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Substrates for glycogen synthesis: In liver: These are converted first to glucose, then to glycogen. In muscles: Glucose molecules are the first activated to uridine diphosphate glucose UDP-G.

Then these UDP-G molecules are added to a glycogen primer to form glycogen. Glucose Is converted Into glucosephosphate by glucokinase in liver and hexokinase In muscles. Formation of glycogen: By the action of glycogen synthase key enzyme of glycogenesis , UDP-G molecules are added to glycogen primer causing elongation of the a branches up to glucose units. It transfers parts of the elongated chains glucose residues to the next chain forming a new o. I-6 glycosidic bond. The new branches are elongated by the glycogen synthase and the process is repeated.

Breakdown of glycogen Glycogenolysis: It is the breakdown of glycogen into glucose in liver and lactic acid in muscles. Phosphorylase the key enzyme of glycogenolysis acts on o. I- 4 bonds, breaking it down by phosphorolysis i.

Therefore, it removes glucose units in the form of glucosephosphate. Phosphorylase enzyme acts on the branches containing more than 4 glucosyl units. When the branch contains 4 glucose units, 3 of them are transferred to a next branch by transferase enzyme, leaving the last one. Carbohydrate metabolism 59 4. The last glucose unit that is attached to the original branch by al-6 bond is removed by debranching enzyme by hydrolysis i.

Glucosephosphate molecules are converted to glucose phosphate, by mutase enzyme. Fate of glucosephosphate: Regulation of glycogenesis and glycogenolysis: There is coordinated regulation of glycogenesis and a glycogenolysis i.

During fasting, glycogenolysis is stimulated and glycogenesis is inhibited. This provides blood glucose from liver glycogen. So after meal, glycogenesis is stimulated and glycogenolysis is inhibited. The principle enzymes controlling glycogen metabolism are glycogen synthase and phosphorylase.

These are regulated as follows: During fasting: Glycogenolysis is stimulated by: This stimulates secretion of epinephrine, nor-epinephrine and glucagon hormones. At the same time , glycogenesis will be inhibited. U After meal II Hormonal regulation of glycogenesis and glycogenolysis. This leads to stimulation of glycogenolysis. After meal: This stimulates secretion of insulin hormone. As a result glycogenesis will proceed and glycogenolysis will be inhibited.

Phosphorylated Phosphatase Adenylot cyclosel I He-. Protein kinase is an enzyme causing phosphorylation of substrate using ATP as a source of phosphate. This enzyme is composed of 4 subunits: The whole protein kinase is inactive, but binding of cAMP with it removes R subunits leaving the active catalytic subunit. Carbohydrate metabolism 63 ['! Differences between liver glycogen and muscle glycogen: Uver Jdycoaen Muscle Jdycoaen Sources: Blood glucose only. It maintains normal blood private source of energy for glucose concentration between muscles only meals End product: Effect of hormone: Stimulates glycogenesis Same Epinephrine: Glycogen storage diseases: These are group of inherited disorders characterized by deposition of abnormal type or quantity of glycogen in the tissues.

They are mainly due to deficiency of one of enzymes of glycogen metabolism e. Type one I: Von Gierk' s disease: This leads to disturbance of liver functions. Oraby's illustrated reviews of biochemistry 64 2. Type two II: Absence of this enzyme in lysosomes results in accumulation of glycogen in all tissues including heart. Death occurs during first year due to heart failure. Type three Ill: Type four IV: Type five V: McArdle's syndrome: This leads to decreased energy.

Type six VI: Her's disease: Type seven VII: Tarui's disease: Type eight VIII: Types of glycogen storage diseases. Carbohydrate metabolism 65 qCuconeogenesis 1. Gluconeogenesis is the formation of glucose from non-carbohydrate sources. These sources include: Some amino acids.

Propionate in ruminants only. Functions of gluconeogenesis: Gluconeogenesis supplies the body with glucose: Glucose is the only source of energy for nervous tissues, RBCs and skeletal muscles during exercises.

Glucose is the precursor of milk sugar lactose in mammary gland. Glucose is important during low carbohydrate diet or when liver glycogen is depleted liver glycogen is depleted after hours. Gluconeogenesis clears the blood from the waste products of other tissues as lactate produced by muscles and RBCs.

Location of gluconeogenesis:: The steps of gluconeogenesis are mainly the reversal of glycolysis, except for the three irreversible kinases which are replaced by the following enzymes: Glycolysis Gluconeogenesis 1.

Glucokinase 1. Glucoseuhosuhatase 2. Fructose 1. This reaction is catalyzed by the enzyme fructose 1,6 bisphosphatase. Glucosephosphate to glucose: This reaction is catalyzed by the enzyme glucosephosphatase.

Pyruvate to phosphoenol pyruvate: This conversion is done by dicarboxylic acid shuttle and needs 2 enzymes: Pyruvate should pass first from cytosol to mitochondria by special transporter. Pyruvate is then converted into oxaloacetate by pyruvate carboxylase in the presence of biotin, COa and ATP. The mitochondrial membrane is impermeable to oxaloacetate. So oxaloacetate is converted to malate by malate dehydrogenase.

Malate is transported to cytosol, where it is converted again into oxaloacetate by cytosolic malate dehydrogenase. Oxaloacetate is converted into phosphoenol pyruvate by phosphoenolpyruvate carboxykinase PEP. Pyruvate never goes in the course of citric acid pathway to reach malate, because this pathway needs insulin and other factors, which are deficient during gluconeogenesis.

Oraby's illustrated reviews of biochemistry 68 v. Pathways for different sources of gluconeogenesis: Any substance that can join common pathway of gluconeogenesis is considered glycogenic. It- --co Fumarat!! Gluconeogenesis from lactate: Lactate is converted into pyruvate by lactate dehydrogenase: Gluconeogenesis from glutamate: Glutamate is converted into a.

Malate then passes out the mitochondria and join common pathway to glucose as indicated in the diagram. Gluconeogenesis from propionic acid: Propionic acid 2. Proplonyl CoA 4.

Gluconeogenesis from! Coenzyme fonn glycerol: Glycerol is mobilized from cobalamin adipose tissue during fasting. Oraby's illustrated reviews of biochemistry 70 cn. Two important c11cles are related to gluconeogenesis: Bnergu cost of gluconeogenesis: Publish Date. Oraby s Medical Biochemistry part 1 - Fast Download.

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Medical Biochemistry Solomon Adugna, Except as expressly provided above, no part of this publication may..

Textbook of biochemistry with clinical correlations, 5 th Ed, Biochemistry-1 Course Specification. Nigella sativa is also used in Armenian string cheese and in a braided string cheese called Majdouleh or Majdouli in the Middle East. Seeds can be ground and used with near abandon like black pepper. Nigellasativa seeds contain 0. To extract volatile oil, crushed seeds are extracted with organic solvents. The solvent is removed and the brownish residue is steam distilled.

Recovery of Nigella sativa essential oil by hydrodistillation gave a yield of 0. Through distillation with the Clevenger apparatus 0.

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Botanical aspects Nigella sativa Linn. Nigella sativa is native to south and southwest Asia wherein the plant is cultivated and grows.Glucokinase 1. Uronic acid pathway: The removal of hydrogen atom or electron from a compound is always accompanied by a release of energy.

Therefore, Jatropha curcas characterized by a rapid growth, low cost of seeds, and high oil content ca. Synthesis of melatonin: Transport of fatty acids Into the mitochondria: N-Fonnamino Type one I: D-Amino acids are absorbed by simple.

Triacylglycerols are digested by a group of enzymes.