top enzymes Flashcards
G6PD
part of hexose monophosphate shunt (HMP)
converts Glucose 6-P to 6-Phosphogluconate
generates 1 NADPH in process (reducing power)
3 features of def:
1) immuno def
2) heinz bodies
3) hemolytic anemia
HMG CoA Reductase
cholesterol synthesis pathway
requires 2 NADPH
Glucagon inhibits by PHOSPHORYLATION
Insulin stimulates by DE-PHOSPHORYLATION
Statin drugs inhibit by COMPETITIVE INHIBITION
side-effects due to statins: accum of farnesyl PPi results in muscle pain, rhabdomylosis
Dihydrofolate reductase
Regenerates THF from DHF - req for dTMP synthesis
Inhibited by:
MTX (euks - RA tx)
Trimethoprim (proks - UTIs)
Primethamine (protozoal)
UDP-Glucoronyl transferase
transfers 2 sugars onto bilirubin to make it soluble
indirect/unconjugated to direct/conjugated
Crigler-Najjar - more severe form of deficinecy
Gilbert - more mild form
Vit K dep carboxylase
adds 2nd carboxyl group to factors II (prothrombin), VII, IX, X, protein C, and protein S. (neg groups attract Ca2+)
inhibited by warfarin
Homocysteine methyl transferase
converts homocysteine to methionine
req methyl-THF, B12 as cofactors
B12, B6, or folate deficiencies result in methyl-THF trap (results in megaloblastic anemia due to dec dTMP synthesis) and accumulation of homocysteine
homocysteine accum = DVT, stroke, Marfan-like habitus, mental retardation
Methyl malonyl CoA mutase
converts methylmalonyl COA to succinyl coA
req B12 cofactor
Hexosaminidase A
cleaves NAc gal from ganglioside
4bp insertion frame shift mutation in Tay-Sachs disease
HGPRT
Purine salvage pathway
converts hypoxanthine or guanine to IMP and GMP
def = Lesch-Nyhan syndrome (X-linked rec)
spastic cerebral palsy
self-mutilation due to painful gouty accum
hyperuricemia
BCKAD
converts branched chain a.a. (after amino group taken off) to acetyl CoA or propionyl CoA
req TLCFN cofactors
def results in MSUD - mental retardation, ketosis, hypoglycemia, burnt orange urine in Amish (Mennonite) populations
Pyruvate dehydrogenase
converts pyruvate to acetyl CoA (in mitochondria)
req TLCFN cofactors, NAD. gives off CO2
inhibited by acetyl CoA
Phenylalanine hydroxylase
metabolizes Phe to Tyr
req THB cofactor
PKU (X-linked recessive)
mentl retardation
mousy odor urine
must avoid aspartame
medium chain fatty acyl-CoA dehydrogenase
beta-oxidizes medium chain fatty acids
def
hypoglycemia with hypoketosis (no ketone bodies) VERY DIAGNOSTIC
inc omega ox
remember liver req beta-ox for the energy it produces, but does not use its carbons!!!
