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:4.1.2.13 (
aldolase
)
3,461
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Tetrahydrofolate
cofactors are required for one carbon transfer reaction involved in the synthesis of purines, amino acids, and thymidine. Inhibition of tetrahydrofolate biosynthesis is a powerful therapeutic strategy in the treatment of several diseases, and the possibility of using antifolates to inhibit enzymes from Mycobacterium tuberculosis has been explored. This work focuses on the study of the first enzyme in tetrahydrofolate biosynthesis that is unique to bacteria, dihydroneopterin aldolase (MtDHNA). This enzyme requires no metals or cofactors and does not form a protein-mediated Schiff base with the substrate, unlike most aldolases. Here, we were able to demonstrate that the reaction catalyzed by MtDHNA generates three different pterin products, one of which is not produced by other wild-type DHNAs. The enzyme-substrate complex partitions 51% in the first turnover to form the
aldolase
products, 24% to the epimerase product and 25% to the oxygenase products. The
aldolase
reaction is strongly pH dependent, and apparent pK(a) values were obtained for the first time for this class of enzyme. Furthermore, chemistry is rate limiting for the
aldolase
reaction, and the analysis of solvent kinetic isotope effects in steady-state and pre-steady-state conditions, combined with proton inventory studies, revealed that two protons and a likely solvent contribution are involved in formation and breakage of a common intermediate. This study provides information about the plasticity required from a catalyst that possesses high substrate specificity while being capable of utilizing two distinct epimers with the same efficiency to generate five distinct products.
...
PMID:One substrate, five products: reactions catalyzed by the dihydroneopterin aldolase from Mycobacterium tuberculosis. 2315 Sep 85
Glycine cleavage system (GCS) occupies a key position in one-carbon (C1) metabolic pathway and receives great attention for the use of C1 carbons like formate and CO
2
via synthetic biology. In this work, we demonstrate that formaldehyde exists as a substantial byproduct of the GCS reaction cycle. Three causes are identified for its formation. First, the principal one is the decomposition of
N
5
,N
10
-methylene-tetrahydrofolate (5,10-CH
2
-
THF
) to form formaldehyde and
THF
. Increasing the rate of glycine cleavage promotes the formation of 5,10-CH
2
-
THF
, thereby increasing the formaldehyde release rate. Next, formaldehyde can be produced in the GCS even in the absence of
THF
. The reason is that T-protein of the GCS can degrade methylamine-loaded H-protein (H
int
) to formaldehyde and ammonia, accompanied with the formation of dihydrolipoyl H-protein (H
red
), but the reaction rate is less than 0.16% of that in the presence of
THF
. Increasing T-protein concentration can speed up the release rate of formaldehyde by H
int
. Finally, a certain amount of formaldehyde can be formed in the GCS due to oxidative degradation of
THF
. Based on a formaldehyde-dependent
aldolase
, we elaborated a glycine-based one carbon metabolic pathway for the biosynthesis of 1,3-propanediol (1,3-PDO) in vitro. This work provides quantitative data and mechanistic understanding of formaldehyde formation in the GCS and a new biosynthetic pathway of 1,3-PDO.
...
PMID:Formaldehyde formation in the glycine cleavage system and its use for an aldolase-based biosynthesis of 1,3-prodanediol. 3246 27
Glycine cleavage system (GCS) occupies a key position in one-carbon (C1) metabolic pathway and receives great attention for the use of C1 carbons like formate and CO
2
via synthetic biology. In this work, we demonstrate that formaldehyde exists as a substantial byproduct of the GCS reaction cycle. Three causes are identified for its formation. First, the principal one is the decomposition of N
5
,N
10
-methylene-tetrahydrofolate (5,10-CH
2
-
THF
) to form formaldehyde and
THF
. Increasing the rate of glycine cleavage promotes the formation of 5,10-CH
2
-
THF
, thereby increasing the formaldehyde release rate. Next, formaldehyde can be produced in the GCS even in the absence of
THF
. The reason is that T-protein of the GCS can degrade methylamine-loaded H-protein (H
int
) to formaldehyde and ammonia, accompanied with the formation of dihydrolipoyl H-protein (H
red
), but the reaction rate is less than 0.16% of that in the presence of
THF
. Increasing T-protein concentration can speed up the release rate of formaldehyde by H
int
. Finally, a certain amount of formaldehyde can be formed in the GCS due to oxidative degradation of
THF
. Based on a formaldehyde-dependent
aldolase
, we elaborated a glycine-based one carbon metabolic pathway for the biosynthesis of 1,3-propanediol (1,3-PDO) in vitro. This work provides quantitative data and mechanistic understanding of formaldehyde formation in the GCS and a new biosynthetic pathway of 1,3-PDO.
...
PMID:Formaldehyde formation in the glycine cleavage system and its use for an aldolase-based biosynthesis of 1,3-propanediol. 3329 16
