Proteins, Enzymes and Coenzyems Flashcards

Question

Types of Reactions: 1. Oxidoreductase 2. Transferase 3. Hydrolase 4. Lyases 5. Isomerase 6. Ligases

Answer 1

1. Redox reactions (dehydrogenase, oxidase, reductase) 2. Transfer of chemical groups (Kinase, transaminase) 3. Cleavage of bonds by addition of water (protease, phosphatase, amylase) 4. Nonhydrolytic cleavage of c-c, c-s and c-n ( aldolase, decarboxylase, dehydratase) 5. Interconversion of isomerse (epimerase, mutase) 6. Formation of bonds c-o, c-n and c-s (carboxylase, thiokinase)

Answer 2

for every 10C increase in temp, the rate increase 2 folds. Beyond optimum temp, the enzyme denatures rapidly and rate decrease

Answer 3

optimum pH is 5-9.

Answer 4

Increase enzyme conc. increases the rate

Answer 5

1. First order: occurs when the conc. of substrate is low. Increasing [S] increases the rate. 2. Zero order: When [S] conc. is high, all the enzyme is saturated and increasing [S] has no effect

Answer 6

Shows the relation between the rate of an enzyme catalyzed reaction and the [S] concentration. v = Vmax * [S] / Km + [S] * Vmax increases with increase in enzyme conc. * Km: is [S] conc. at which the reaction runs at half Vmax

Answer 7

False.. Km is independent

Answer 8

more accurate than Michaelis-Menten in giving Vmax and Km. Obtained by taking the reciprocal of Michaelis-Menten equation see p. 444

Answer 9

means that the enzyme has high affinity to [S]

Answer 10

1. Competitive: structural analogs to [S] and compete with it for binding site. Overcome by increasing [S]. Km will be increased.. Vmax is the same. slope increases 2. Non competitive: binds to a different active site. Vmax decrease. Km is the same. The slope increases. Can't be overcome by increasing [S]. It is an allosteric inhibitor for the reaction 3. Uncompetitive: binds to enzyme-substrate complex, rendering the enzyme inactive. Vmax and Km decrease. Slope remains the same see p.446

Answer 11

covalently binds to enzyme causing its permanent inactivation. Their effect on kinetics is the same as noncompetitive inhibitor. Lead toxicity is an example of decreasing synthesis of heme.

Answer 12

Regulatory enzymes which catalyzes the rate limiting reactions of a pathway or an irreversible reaction

Answer 13

1. Allosteric: reversible binding of an effector molecule to a site other than the active site on the enzyme. Positive effectors increase Vmax & decrease Km. Negative ones decrease Vmax & increase Km. (examples AMP, NADH, NAD+ etc..). Michalis menten kinetics are not followed 2. Covalent modification: phosphorylation/dephosphorylation by modifying serine, threonine or tyrosine side chains with kinase or phosphatase. Phosphorylation may increase or decrease the enzyme activity, or it might change its regulatory properties. 3. Isoenzymes: they catalyze the same reaction but have different regulatory and catalytic properties. They aid in fine tuning of enzyme function. 4. Induction and repression of enzyme synthesis: this process is usually mediated by steroids or thyroid hormones that act on the nucleus.

Answer 14

Redox and transfer reactions

Answer 15

Small organic molecules, more stable than proteins. Derived from vitamins. Comprising all of the water soluble and some of the fat soluble vitamins. * It is the non protein potion of an enzyme

Answer 16

apoenzyme + Coenzyme | * Apoenzyme is the same as enzyme

Answer 17

three alpha-chains wound around each other, forming a triple helix * It is the main organic matrix in dentin and cementum * Its synthesis requires vitamin C

Answer 18

B2, B7, B12, Vit K, folic acid

Answer 19

body fat | eliminated in urine

Answer 20

``` intestinal bacteria tryptophan pyridine (deficiency associated with oral contraceptives use) ```

Proteins, Enzymes and Coenzyems Flashcards

(44 cards)