Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:3.4.21.64 (
proteinase K
)
4,071
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
UDP-glucose dehydrogenase
(
UGDH
) catalyzes the conversion of UDP-glucose to UDP-glucuronic acid by NAD
+
-dependent two-fold oxidation. Despite extensive investigation into the catalytic mechanism of
UGDH
, the previously proposed mechanisms regarding the first-step oxidation are somewhat controversial and inconsistent with some biochemical evidence, which instead supports a mechanism involving an NAD
+
-dependent bimolecular nucleophilic substitution (S
N
2) reaction. To verify this speculation, the essential Cys residue of
Streptococcus zooepidemicus
UGDH
(
Sz
UGDH
) was changed to an Ala residue, and the resulting Cys260Ala mutant and
Sz
UGDH
were then co-expressed
in vivo
via a single-crossover homologous recombination method. Contrary to the previously proposed mechanisms, which predict the formation of the capsular polysaccharide hyaluronan, the resulting strain instead produced an amide derivative of hyaluronan, as validated via
proteinase K
digestion, ninhydrin reaction, FT-IR and NMR. This result is compatible with the NAD
+
-dependent S
N
2 mechanism.
...
PMID:UDP-glucose Dehydrogenase: The First-step Oxidation Is an NAD
+
-dependent Bimolecular Nucleophilic Substitution Reaction (S
N
2). 3074 25
