CHEMISTRY OF ENZYMES

1. CHEMISTRY OF ENZYMES Mrs. Chaitali Maitra Assistant Professor Dept.of Biochemistry PCMS&RC

2. TO MY STUDENTS HERE I HAVE TRIED TO SIMPLIFY THE HUGE SUBJECT WITH ANIMATIONS, DIAGRAMS, FLOW CHARTS & RELEVENT MCQs. DIFFERENT TEXT BOOKS AND REFERENCE BOOKS HAVE BEEN USED FOR PREPARING THE CONTENTS. REMEMBERTHESE SLIDES ARE NOT THE SUBSTITUTE OF YOUR TEXT BOOKS ANIMATIONS AND DIAGRAMS ARE COLLECTED FROM DIFFERENT WEBSITE SOLELY FOR EDUCATION PURPOSE.

3. DEFINITION THEY ARE PROTEIN CATALYST THAT INCREASES THE RATE OF BIOLOGICAL REACTION WITHOUT BEING CHANGED IN THE OVERALL PROCESS. THEY ARE HEAT LABILE COLLOIDAL AND SOLUBLE IN WATER. HALOENZYME: ENZYMES SIMPLE COMPLEX WITH NON PROTEIN PART HOLOENZYME:ACTIVE ENZYME(APOENZYME) + NON PROTEIN PART(COFACTOR). ORGANIC(COENZYME OR PROSTHETIC GROUP) NON-PROTEIN PART INORGANIC(METAL IONS) EXCEPTION: RNA ENZYME OR RIBOZYME

4. COENZYME: THEY ARE THERMOSTABLE , LOW MOL. WT., NON PROTEIN ORGANIC SUBSTANCES, LOOSELY ATTACHED TO APOENZYME,SEPERATED EASILY BY DIALYSIS. THEY ARE OFTEN CALLED COSUBSTRATE OR SECONDARY SUBSTRATE. REACTION INVOLVING OXIDOREDUCTION,GRP. TRANSFER,ISOMERIZATIONAND COVALENT BOND FORMATION REQ. COENZYME. CLASSIFICATION: ACCORDING TO THE GROUP THEY TRANSFER 1.COENZYME TACKING PART IN REACTION CATALYSED BY OXIDOREDUCTASES , DONATE OR ACCEPT HYDROGEN ATOMS OR ELECTRONS NAD-NADH COENZYME Q NADP-NADPH LIPOIC ACID FAD-FADH2 FMN-FMNH2

5. ROLE OF METAL ION IN ENZYMES ~SOME CONTAIN DEFINITE QUANTITY OF FUNCTIONAL METAL ION THAT IS TIGHTLY BOUND. e.g. COPPER IN TYROSINASE.THEY ARE CALLED METALLOENZYME ~IN CASE OF METAL ACTIVATED ENZYME IONS ARE BOUND LOOSELY.e.g. CHLORINE & FLOURINE WILL ACTIVATE SALIVARY AMYLASE

6. CLASSIFICATION OF ENZYMES CLASSIFIED BY IUBMB BASED ON REACTION TYPE AND MECHANISM NAME HAS 2 PARTS---FIRST SUBSTRATE & SECOND PART END IN –ase INDICATING TYPE OF REACTION THERE ARE 6 CLASSES THE ENZYME COMMISSION NUMBER (EC NUMBER) IS A NUMERICAL CLASSIFICATION SCHEME FOR ENZYMES, BASED ON THE CHEMICAL REACTIONS THEY CATALYZE. AS A SYSTEM OF ENZYME NOMENCLATURE, EVERY EC NUMBER IS ASSOCIATED WITH A RECOMMENDED NAME FOR THE RESPECTIVE ENZYME. IT IS A 4 DIGIT CODE HEXOKINASE(2.7.1.1) HERE, 2. IS CLASS(TRANSFERASE) 7. IS SUBCLASS (TRANSFER OF PHOSPHATE) 1. IS SUB-SUBCLASS(ALCOHOL IS PHOSPHATE ACCEPTOR) 1. SPECIFIC NAME ATP,D-HEXOSE-6-PHOSPHOTRANSFERASE

7. CLASSES OF ENZYMES

10. HOW DOES ENZYME WORK? LOWERING OF ACTIVATION ENERGY EACH REACTION HAS A TRANSITION STATE WHERE THE SUBSTRATE IS IN AN UNSTABLE, SHORT-LIVED CHEMICAL/STRUCTURAL STATE. FREE ENERGY OF ACTIVATION IS SYMBOLIZED BY ΔG‡. DG IS THE DIFFERENTIAL IN FREE ENERGY BETWEEN THE PRODUCTS VS. REACTANTS IF DG < 0, REACTION IS ENERGETICALLY FAVORABLE I.E., REACTANTS WILL CONVERT TO PRODUCTS AS SYSTEM MOVES TO EQUILIBRIUM ENZYMES ACT BY LOWERING THE FREE ENERGY OF THE TRANSITION STATE

11. ENZYME SUBSTRATE COMPLEX THEORY LOCK AND KEY THEORY

12. INDUCED FIT MODEL EXPLAIN FLEXIBILITY OF ENZYME

13. ACTIVE SITE USUALLY OCCUR IN CLEFTS AND CREVICES TO WHICHTHE SUBSTRATE BIND. AMINO ACIDS AND COFACTORS ARE HELD IN PRECISE ARRANGEMENT WITH RESPECT TO STRUCTURE OF THE SUBSTRATE. ACTIVE SITE CONSISTS OF ATOMS ON RESIDUE SIDE CHAINS THAT ARE BROUGHT TOGETHER BY THE FOLD ACTIVE SITE USES RANGE OF NONCOVALENT BONDING MECHANISMS TO BIND SUBSTRATE SMALL RELATIVE TO THE TOTAL VOLUME OF THE ENZYME. THE SPECIFICITY OF SUBSTRATE UTILIZATION DEPENDS ON THE DEFINED ARRANGEMENT OF THE ATOMS IN THE ENZYME ACTIVE SITE (COMPLEMENTS THE STRUCTURE OF THE SUBSTRATE MOLECULE).

14. 2. COENZYMES TAKING PART IN REACTIONS TRANSFERING GROUP OTHER THAN HYDROGEN SUGAR PHOSPHATE---PHOSPHATE GRP CoA-SH—ACYL GRP THIAMINE PYROPHOSPHATE---HYDROXYETHYL PYRODOXALPHOSPHATE---AMINO GRP. FOLATE COENZYME---ONE C GRP. BIOTIN---CARBONDIOXIDE COBAMIDE COENZYME—METHYL COBALAMIN SPECIAL SUBSET OF COENZYMES ARE PROSTHETIC GROUPS. THESE HAVE MORE IN COMMON WITH COFACTORS SINCE THEY ARE TIGHTLY BOUND TO ENZYMES AND ARE NOT RELEASED AS PART OF THE REACTION. PROSTHETIC GROUPS INCLUDE MOLYBDOPTERIN, LIPOAMIDE AND BIOTIN.

15. ENZYMES EMPLOY MULTIPLE MECHANISMS TO FACILITATE CATALYSIS FOUR GENERAL MECHANISMS TO ACHIEVE DRAMATIC CATALYTIC ENHANCEMENT OF THE RATES OF CHEMICAL REACTIONS. CATALYSIS BY PROXIMITY CREATES A REGION OF HIGH LOCAL SUBSTRATE CONCENTRATION. ORIENTS THE SUBSTRATE MOLECULES SPATIALLY IN A POSITION IDEAL FOR THEM TO INTERACT, ACID-BASE CATALYSIS THE IONIZABLE FUNCTIONAL GROUPS OF AMINOACYL SIDE CHAINS AND (WHERE PRESENT) OF PROSTHETIC GROUPS CONTRIBUTE TO CATALYSIS BY ACTING AS ACIDS OR BASES. e.g. Enzymes of the aspartic protease family. CATALYSIS BY STRAIN REACTIONS THAT INVOLVE BREAKING A COVALENT BOND TYPICALLY BIND THEIR SUBSTRATES IN A CONFORMATION SLIGHTLY UNFAVORABLE FOR THE BOND THAT WILL UNDERGO CLEAVAGE. COVALENT CATALYSISTHE PROCESS OF COVALENT CATALYSIS INVOLVES THE FORMATION OF A COVALENT BOND BETWEEN THE ENZYME AND ONE OR MORE SUBSTRATES. THE MODIFIED ENZYME THEN BECOMES A REACTANT.. ON COMPLETION OF THE REACTION, THE ENZYME RETURNS TO ITS ORIGINAL UNMODIFIED STATE. E.g.Chymotrypsin

16. SPECIFICITY OF ENZYME • OPTICAL SPECIFICITY • SOME ARE ISOMER SPECIFIC e.g D- & L- AMINO ACID,SUCCINIC DEHYDROGENASE GIVES FUMARIC ACID NOT MALIC ACID FORM SUCCINIC ACID. • 2. REACTION SPECIFICITY • 3. SUBSTRATE SPECIFICITY • ABSOLUTE e.g. UREASE • RELATIVE • GROUP DEPENDENT e.g. TRYPSIN(LYSINE & ARGININE) • BOND DEPENDENT e.g. CHYMOTRYPSIN(AROMATIC) • 4. BOND SPECIFICITY • IN THE CASE OF PROTEOLYTIC ENZ. e.g. GLYCOSIDASE(GLYCOSIDIC BOND) LIPASE(ESTER BOND).

17. FACTORS EFFECTING ENZYME ACTIVITY • TEMPERATURE • BELL SHAPED CURVE • OPTIMAL TEMPERATURE • DENATURATION AT HIGH TEMPERATURE

18. 2.EFFECT OF pH BELL SHAPED CURVE CHARGE OF AMINO ACID RESIDUE AT ACTIVE SITE ENZYME HAVE OPYIMUM pH BETWEEN 6-8. EXCEPTIONS: PEPSIN(1-2),ALKALINE PHOSPHATASE(9-10),ACID PHOSPHATASE(4-5)

19. 3.EFFECTS OF ENZYME CONCENTRATION ~VELOCITY OF REACTION INCREASES PROPORTIONALLY WITH CONC. OF ENZYME PROVIDED SUBSTRATE CONCENTRATION IS UNLIMITED ~PROPERTY IS USED IN DETERMINATION OF LEVEL OF SERUM ENZYME(END-POINT) ~KINETIC TECHNIQUE. RATE OF REACTION V [ E ]

20. 4.EFFECT OF CONCENTRATION OF PRODUCT ~IN REVERSIBLE REACTION,WHEN EQUILIBRIUM IS REACHED REACTION SLOW DOWN ~ STOPPED OR EVEN REVERSED E1 E2 E3 A B C D ACCUMULATION

21. 5.EFFECTS OF SUBSTRATE CONCENTRATION WITH RISE IN SUBSTRATE CONCENTRATION INITIAL VELOCITY RISES UNTILL IT REACHES MAXIMUM LATER NO INCREASE IN VELOCITY OF REACTION.

22. NO MATTER HOW LARGE THE SUBSTRATE CONCENTRATION,REACTION RATE CAN NEVER EXCEED VMAX. Km IS THE SUBSTRATE CONCENTRATION AT WHICH REACTION RATE IS HALF MAXIMAL. Km REFLECTS THE BINDING AFFINITY OF THE ENZYME FOR THE SUBSTRATE; THE HIGHER THE AFFINITY, THE SMALLER IS KM.

23. MICHAELIS-MENTEN EQUATION Km IS CALLED MICHAELIS CONSTANT & IT IS INDEPENDENT OF ENZYME CONC. Km IS CONSTANT FOR ENZYME. IT IS EXPRESSED IN moles/L. LINEWEAVER-BURK PLOT OR THE DOUBLE RECIPROCAL PLOT. USEFUL FOR EXPERIMENTAL DETERMINATION OF KM AND VMAX

24. HILL’S EQUATION FOR COOPERATIVE BINDING PROPERTY OF MULTYMERIC ENZYME V [ S ]

25. ENZYME INHIBITION MANY SMALL MOLECULES CAN BIND TO ENZYMES AND INHIBIT THEM. INHIBITORS CAN BE DESCRIBED AS REVERSIBLE OR IRREVERSIBLE. INHIBITORS MAY BE NATURALLY OCCURING WITHIN THE HOMOLOGOUS ORGANISM OR IN A HETEROLOGOUS ORGANISM OTHER INHIBITORS ARE SYNTHETIC AND HAVE BEEN DEVELOPED AS PHARMACEUTICALS FOR RESEARCH AND CLINICAL APPLICATIONS TYPES COMPETITIVE NON-COMPETITIVE UNCOMPETITIVE SUICIDE

26. COMPETITIVE INHIBITION INHIBITOR COMPETE WITH SUBSTRATE STRUCTURAL ANALOGUE OF SUBSTRATE INHIBITION IS REVERSIBLE INHIBITOR DOES NOT BIND WITH ES COMPLEX INHIBITION IS RELEIVED IN EXCESS SUBSTRATE CONCENTRATION

27. COMPETITIVE INHIBITION: Km INCREASED,V-MAX NO CHANGE LACTATE DEHYDROGENASE: LACTATE ,OXAMATE SUCCINATE DEHYDROGENASE : SUCCINATE, MALONATE CLINICAL USE : METHOYREXATE,METHANOL,ALLOPURINOL,LOVASTATIN

28. NON-COMPETITIVE INHIBITION NOT RESEMBLE SUBSTRATE BINDS TO SITE OTHER THAN ACTIVE SITE CAN BIND WITH ES COMPLEX USUALLY IRREVERSIBLE INCREASING SUBSTRATE CONCENTRATION WILL NOT ABOLISH INHIBITION

29. NON COMPETITIVE INHIBITION : Km NO CHANGE , V-MAX DECREASED CYTOCHROME OXIDASE :CYANIDE FLOURIDE : ENOLASE IODOACETATE : SH ENZYME HEAVY METAL, OXIDISING AGENTS

30. UNCOMPETITIVE INHIBITION INHIBITOR HAS NO AFFINITY FOR FREE ENZYME BINDS TO ES COMPLEX

31. 1 Km UNCOMPETITIVE INHIBITION : BOTH Km & V-MAX DECREASED INHIBITION OF PLACENTAL ALKALINE PHOSPHATASE (REGAN ISOENZYME) BY PHENYLALANINE.

32. SUICIDE INHIBITION SPECIAL TYPE OF IRREVERSIBLE INIHIBITION STRUCTURAL ANALOGUE IS CONVERTED TO MORE EFFECTIVE INHIBITOR BY ENZYME TO BE INHIBITED ALSO KNOWN AS MECHANISM BASED INHIBITION e.g. ALLOPURINOL OXIDISED BY XANTHINE OXIDASE TO ALLOXANTHINE WHICH IS A MORE STRONG INHIBITOR

33. REGULATION OF ENZYME ACTIVITY THE RATES OF ENZYME-CATALYZED REACTIONS ARE ALTERED BY ACTIVATORS AND INHIBITORS (A.K.A. EFFECTOR MOLECULES). ALLOSTERIC REGULATION

34. MIXED KIND OF INHIBITION NIHIBITOR IS NOT SUBSTRATE ANALOGUE BINDS TO SITE OTHER THAN ACTIVE SITE ALLOSTERIC ACTIVATION BY POSITIVE MODIFIER AND INHIBITION BY NEGATIVE MODIFIER. +VE & --VE COOPERATIVITY MOST ALLOSTERIC ENZYME POSSESS QUATERNARY STRUCTURE UTILISED BY BODY TO REGULATE METABOLIC PATHWAYS ALLOSTERIC INHIBITOR IS MOST EFFECTIVE WHEN SUBSTRATE CONC. IS LOW

35. INHIBITION :Km INCREASED V-MAX REDUCED PHOSPHOFRUCTO KINASE : ATPAMP ACETYL CoA CARBOXYLASE : ACYL CoACITRATE ALA SYNTHASE : HEME PYRUVATE CARBOXYLASE : ADPACETYL CoA

36. COVALENT MODIFICATION INCREASE OR DECREASE THE ACTIVITY OF ENZYME GROUP IS ADDED BY COVALENT BOND OR REMOVED BY BREAKING COVALENT BOND ZYMOGEN ACTIVATION (CHEMOTRYPSIN) PHOSPHORYLATION – DEPHOSPHORYLATION (GLYCOGEN SYNTHASE IS INACTIVE IN PHOSPHORYLATED STATE GLYCOGEN PHOSPHORYLASE IS ACTIVE IN PHOSPHORYLATED STATE) PHOSPHORYLATION ACTIVATES : HMG COA REDUCTASE KINASE,CITRATE LYASE,PHOSPHORYLASE B KINASE DEPHOSPHORYLATION ACTIVATES : ACETYL COA CARBOXYLASE,PYRUVATE KINASE,PFK2 METHYLATION ADENYLATION ACYLATION

37. FEED BACK INHIBITION END PRODUCT INHIBITION ACTIVITY OF ENZYME IS INHIBITED BY END PRODUCT OF THE PATHWAY. AMP INHIBIT THE FIRST STEP OF PURINE SYNTHESIS

38. ISO-ENZYMES CATALYZE THE SAME REACTION TWO OR MORE POLYPEPTIDE CHAINS DIFFERENT POLYPEPTIDE CHAINS ARE PRODUCTS OF DIFFERENT GENES DIFFER IN AMINO ACID SEQUENCE AND PHYSICAL PROPERTIES MAY BE SEPARABLE ON THE BASIS OF CHARGE ARE TISSUE SPECIFIC

40. CLINICAL ENZYMOLOGY PLASMA CONTAIN FUNCTIONAL AND NON FUNCTIONAL ENZYME NON FUNCTIONAL ENZYME COME OUT DURING NORMAL WEAR AND TEAR OF CELLS AND TISSUE. IN HEALTHY INDIVIDUALS LEVEL OF THESE ENZYME ARE FAIRLY CONSTANT INCREASE IN PLASMA LEVEL INDICATES TISSUE DAMAGE ENZYME UNITS ONE INTERNATIONAL UNIT IS THE AMOUNT OF ENZYME THAT WILL CONVERT ONE MICROMOLE OF SUBSTRATE PER MINUTE PER LITRE OF SAMPLE AND IS ABBREVIATED AS IU/L

41. LACTATE DEHYDROGENASE (LDH) CONVERTS PYRUVATE TO LACTATE (AND VICE VERSA) NORMAL LEVEL:100-200 IU/L.(HIGH IN RBC’S) LDH OCCURS AS A TETRAMER OF 2 DIFFERENT SUBUNITS H & M: (PRODUCT OF 2 DIFF. GENE)         LD-1 (HHHH)H4 FROM THE HEART:(ELEVATED AFTER MYOCARDIAL INFRACTION)         LD-2 (HHHM)H3M1 FROM RBC:         LD-3 (HHMM)H2M2 BRAIN: LD-4 (HMMM)M3H1 LIVER LD-5 (MMMM)M4, SKELETAL MUSCLE: NORMAL LDH2 IS HIGH IN SERUM BUT AFTER MI LDH1 RISES(FLIPPED PATTERN) INCREASE OF TOTAL IS SEEN IN HEMOLYTIC ANEMIA,HEPATOCELLULAR DAMAGE,CARCINOMAS,LEUKEMIAS & ANY CONDITION OF NECROSIS.

42. CREATINE KINASE (CK) CREATINE KINASE IS ASSOCIATED WITH ATP REGENERATION IN MUSCLE AND NERVOUS TISSUE. NORMAL LEVEL:15-100U/L IN MALES,10-80 U/L IN FEMALES. ELEVATED BLOOD LEVELS OF CK ARE USED AS INDICATORS OF MI(FIRST ENZYME TO RISE 3HR), MUSCULAR DYSTROPHY, AND STROKE. CK OCCURS AS A DIMER OF 2 DIFFERENT SUBUNITS, M AND B.         - CK-BB: BRAIN         - CK-MB: HEART         - CK-MM: MUSCLE THESE CAN BE SEPARATED BY ELECTROPHORESIS. CK-MB IS RELEASED FROM CARDIAC MUSCLE CELLS AFTER MI.(NOT INCREASED BY HEMOLYSIS OR CONGESTIVE HEART FAILURE.

43. ASPARTATE AMINOTRANSFERASE (AST) OR SGOT • THIS ENZYME IS WIDELY DISTRIBUTED IN THE BODY. • NORMAL LEVEL 8-20 U/L • MAIN SOURCES: HEART, LIVER, SKELETAL MUSCLE, AND KIDNEY. • USEFUL IN THE DIAGNOSIS OF MI(RISES AFTER CK IN MI), LIVER DISORDERS AND MUSCLE DAMAGE. • 2 ISOENZYME FORM : MITOCHONDRIAL AND CYTOPLASMIC. • CAUSES OF SERUM AST LEVELS: • PHYSIOLOGICAL : NEONATES. • LIVER DISEASES: HEPATITIS, HEPATIC NECROSIS , CHOLESTASIS • CARDIAC DISEASE: MYOCARDIAL INFARCTION. • DISEASES OF SKELETAL MUSCLE: CRUSH INJURY,TRAUMA,MYOPATHY • FROM ERYTHROCYTES: HEMOLYSIS

44. ALANINE AMINOTRANSFERASE (ALT) OR SGPT WIDELY DISTRIBUTED, ALTHOUGH THE LARGEST AMOUNTS FOUND IN THE LIVER. NORMAL LEVEL:13-40 U/L IN MALES, 10-30 U/L IN FEMALES. SMALLER AMOUNTS OCCUR IN THE HEART BUT USUALLY REMAINS NORMAL AFTER MI . CONGESTIVE CARDIAC FAILURE RELEASE FROM THE LIVER MORE SPECIFIC FOR LIVER DISEASE THAN AST. ACUTE HEPATITIS >CIRRHOSIS , MALIGNANCY.

45. GAMMA-GLUTAMYLTRANSFERASE (GGT) • A MICROSOMAL ENZYME ITS SYNTHESIS INDUCED BY ETHANOL AND ANTICONVULSANT DRUGS. • NORMAL SERUM LEVEL:10-30 U/L • FOUND MAINLY IN THE KIDNEY AND SIGNIFICANT AMOUNTS IN LIVER, BRAIN, PROSTATE, AND PANCREAS • . • USED PRIMARILY FOR DIAGNOSIS OF HEPATOBILIARY PROBLEMS. • ALT, AST AND GGT ARE THE MAIN LIVER FUNCTION TESTS. • MARKED ELEVATION OF SERUM GGT LEVEL IS SEEN IN ALCOHOLIC LIVER DISEASE. • SERUM GGT ACTIVITY SOMETIMES FOLLOWING MI OR CONGESTIVE CARDIAC FAILURE. HAS 11 ISOMERS

46. ACID PHOSPHATASE (ACP) • HYDROLYSES PHOSPHORIC ACID ESTER AT pH 4-6. • NORMAL LEVEL: 2.5-12 U/L • PRIMARILY USED TO DIAGNOSE PROSTATE CANCER. • IN OTHER PROSTATIC CONDITIONS E.G. PROSTATITIS, BENIGN PROSTATIC HYPERTROPHY. • IN OTHER NON PROSTATIC CONDITIONS E.G. HEMOLYSIS, PAGET’S DISEASE, METASTATIC CARCINOMA OF THE BREAST & GAUCHER’S DISEASE. • PROSTATE- SPECIFIC ANTIGEN(PSA): AN ENZYME OCCURS IN PROSTATIC TISSUE AND  IN CASES OF METASTATIC CARCINOMA • TARTARATE INHIBITS THE PROSTATIC ACP ENZYME WHILE FORMALDEHYDE INHIBITS ACP FROM OTHER SOURCES

47. ALKALINE PHOSPHATASE (ALP) WIDELY DISTRIBUTED, HIGH CONCENTRATIONS IN INTESTINES, LIVER, BONE, SPLEEN, PLACENTA AND KIDNEY. OPTIMUM pH FOR ACTIVITY: 9-10 NORMAL LEVEL:40-125 U/L ,UPPER LEVEL OF CHILDREN IS MORE. THE MAIN SOURCES OF SERUM ALP ARE THE HEPATOBILIARY TREE DYSFUNCTION AND BONE DISORDERS. ELEVATED LEVELS DURING HEALING OF FRACTURES , ACTIVE GROWTH AND DURING THE 3RD TRIMESTER OF PREGNANCY.  SERUM ALP ACTIVITY IN LIVER DISEASE IS MAINLY DUE TO CHOLESTASIS. DECREASED LEVELS ARE FOUND IN THE INHERITED CONDITION “ HYPOPHOSPHATASIA” WHICH IS CAUSED BY DEFECTIVE BONE CALCIFICATION

48. GLUCOSE 6-PHOSPHATE DEHYDROGENASE (G6PD) FIRST (AND CONTROL) ENZYME FOR PENTOSE PHOSPHATE PATHWAY (P.P.P.). NORMAL LEVEL:125-250 U/1012 RBC CELLS IMPORTANT IN PRODUCTION OF NADPH + H+, ESPECIALLY IN RBC. NADPH + H+ KEEPS GLUTATHIONE REDUCED. ANTIMALARIAL DRUGS ARE OXIDANTS, AND ADVERSELY AFFECT THIS SYSTEM IN RBCS. SOME POPULATIONS, ESPECIALLY AFRICAN-AMERICANS, HAVE A HIGH FREQUENCY OF G6PD DEFICIENCY. IF GIVEN ANTIMALARIAL DRUGS, OR FAVA BEANS, THEY DEVELOP HEMOLYTIC ANEMIA.

49. AMYLASE (AMS) HYDROLASES THAT SPLIT COMPLEX POLYSACCHARIDES. - ALPHA-AMYLASES (1-4 ALPHA LINKS ATTACKED AT RANDOM) - MW 40,000 - FILTERED BY KIDNEY - CA+2 REQUIRING METALLOENZYME NORMAL LEVEL:50-120 U/L INCREASES DRASTICALLY IN ACUTE PANCREATITIS ALSO IN MUMPS SOURCES : 1.    PANCREAS (P-TYPE) 2.    SALIVARY GLANDS (S-TYPE) 3.    INTESTINAL MALIGNANCY    CLINICAL SIGNIFICANCE : DIAGNOSIS AND MONITORING OF PANCREATITIS

50. LIPASE BREAKS DOWN FAT INTO MONOACYLGLYCEROL AND FREE FATTY ACIDS . PRIMARILY FROM THE PANCREAS. NORMAL LEVEL: 0.2-1.5 U/L USED TO DIAGNOSE ACUTE PANCREATITIS. PANCREATIC LIPASES : - A GROUP OF ENZYMES THAT HYDROLYZE GLYCEROL ESTERS OF LONG CHAIN FATTY ACIDS. - SOME SUBSTRATE SPECIFICITY E.G. LPL (LIPOPROTEIN LIPASE). - BILE SALTS ARE NECESSARY FOR ACTIVITY. -ALMOST EXCLUSIVELY USED CLINICALLY IN THE INVESTIGATION OF PANCREATITIS. - INCREASE WITHIN 2 - 12 HOURS OF ACUTE ATTACK. - MAY REMAIN ELEVATED FOR MANY DAYS . - MORE SPECIFIC TO ACUTE PANCREATITIS THAN AMYLASE. - LESS SENSITIVE TO ACUTE EXACERBATIONS IN CHRONIC PANCREATITIS.