Loading....
Coupon Accepted Successfully!

Biochemistry

Open Flashcards

Enzymes

Question
17 out of 79
 

The reaction inhibited in thiamine deficiency is



A Pyruvate to Acetyl COA

B Citrate to alpha ketoglutarate

C Succinyl CoA to fumarate

D None

Ans. A Pyruvate to Acetyl CoA

Pyruvate dehydrogenase A multiple -complex enzyme

a. Pyruvate dehydrogenase is inhibited by its products, Acetyl-CoA and NADH

b. Arsenite or mercuric ions complex the — SH gp of Lipoic acid and inhibit pyruvate dehydrogenase as does

i. dietary deficiency of thiamine (i.e. inhibit pyruvate to Acetyl CoA conversion), Allow pyruvate to

accumulate leads to lactic acidosis * same things happen in inherited deficiency of pyruvate

dehydrogenase.

c. Active thiamine is thiamine diphosphate (TPP). TPP is a co-enzyme in enzymatic reactions which an activated aldehyde unit is transferred eg.

a. Oxidative decarboxylation: - eg.

i. α-keto acid (α-keto dehydrogenase)

ii. Pyruvate ( Pyruvate dehydrogenase)

iii. α-keto analogs of (Leucine, iso Leucine and valine α-keto acid decarboxylase

b. (ii) Also required in Tryptophan metabolism by Tryptophan pyrrolase

c. (iii) Transketolase reaction: - in HMP path:

All these reaction are inhibited in thiamine deficiency.

Enzymes Flashcard List

79 flashcards
1)
2)
3)
4)
5)
6)
7)
8)
9)
10)
11)
12)
13)
14)
15)
16)
17)
18)
19)
20)
21)
22)
23)
24)
25)
26)
27)
28)
29)
30)
31)
32)
33)
34)
35)
36)
37)
38)
39)
40)
41)
42)
43)
44)
45)
46)
47)
48)
49)
50)
51)
52)
53)
54)
55)
56)
57)
58)
59)
60)
61)
62)
63)
64)
65)
66)
67)
68)
69)
70)
71)
72)
73)
74)
75)
76)
77)
78)
79)