Literature summary for 4.2.1.22 extracted from

Singh, S.; Madzelan, P.; Stasser, J.; Weeks, C.L.; Becker, D.; Spiro, T.G.; Penner-Hahn, J.; Banerjee, R.
Modulation of the heme electronic structure and cystathionine beta-synthase activity by second coordination sphere ligands: The role of heme ligand switching in redox regulation (2009), J. Inorg. Biochem., 103, 689-697.

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Cloned(Commentary)

Cloned (Comment)	Organism
expressed as a GST-fusion protein in Escherichia coli	Homo sapiens

Protein Variants

Protein Variants	Comment	Organism
H67A	mutant is comparable to wild-type, specific activity and Km values for L-Ser, L-homocysteine comparable to wild-type	Homo sapiens
R266G	patient mutation , mutant protein shows instability and extensive degradation during thrombin treatment. A GST-R266G fusion protein does not exhibit any detectable activity unlike the GST-tagged wild-type CBS	Homo sapiens
R266K	mutant is moderately pyridoxal 5'-phosphate responsive, Km value for serine is slightly elevated compared to wild-type CBS, Km value for homocysteine slightly lower compared to wild-type	Homo sapiens
R266M	R266M mutant shows a significantly lower basal activity, Km value for serine is slightly elevated compared to wild-type CBS, Km value for homocysteine slightly lower compared to wild-type, R266M mutant shows dramatic differences in the ferrous state. The electrostatic interaction between C52 and R266 is critical for stabilizing the ferrous heme and its disruption leads to the facile formation of a 424 nm (C-424) absorbing ferrous species, which is inactive, compared to the active 449 nm ferrous species for wild-type CBS. Resonance Raman studies on the R266M mutant reveal that the kinetics of C52 rebinding after Fe-CO photolysis are comparable to that of wild-type CBS	Homo sapiens

Inhibitors

Inhibitors	Comment	Organism	Structure
CO	-	Homo sapiens
HgCl2	-	Homo sapiens

KM Value [mM]

KM Value [mM]	KM Value Maximum [mM]	Substrate	Comment	Organism	Structure
1.3	-	L-homocysteine	mutant R266K	Homo sapiens
1.6	-	L-homocysteine	mutant R266K	Homo sapiens
2	-	L-cysteine	wild-type	Homo sapiens
3.4	-	L-homocysteine	mutant H67A	Homo sapiens
4.4	-	L-cysteine	mutant R266K	Homo sapiens
5	-	L-homocysteine	wild-type	Homo sapiens
5.4	-	L-cysteine	mutant H67A	Homo sapiens
5.5	-	L-cysteine	mutant R266K	Homo sapiens

Organism

Organism	UniProt	Comment	Textmining
Homo sapiens	-	-	-

Purification (Commentary)

Purification (Comment)	Organism
using a glutathione sepharose column	Homo sapiens

Specific Activity [micromol/min/mg]

Specific Activity Minimum [µmol/min/mg]	Specific Activity Maximum [µmol/min/mg]	Comment	Organism
0.68	-	without pyridoxal 5'-phosphate, without S-adenosyl-L-methionine, mutant R266M	Homo sapiens
1.91	-	without pyridoxal 5'-phosphate, without S-adenosyl-L-methionine, mutant R266K	Homo sapiens
2.31	-	without pyridoxal 5'-phosphate, without S-adenosyl-L-methionine, mutant H67A	Homo sapiens
3.6	-	without pyridoxal 5'-phosphate, without S-adenosyl-L-methionine, wild-type	Homo sapiens
3.9	-	with pyridoxal 5'-phosphate, with S-adenosyl-L-methionine, mutant R266M	Homo sapiens
5.2	-	with pyridoxal 5'-phosphate, with S-adenosyl-L-methionine, mutant H67A	Homo sapiens
5.2	-	with pyridoxal 5'-phosphate, with S-adenosyl-L-methionine, wild-type	Homo sapiens
5.71	-	with pyridoxal 5'-phosphate, with S-adenosyl-L-methionine, mutant R266K	Homo sapiens

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
L-cysteine + L-homocysteine	-	Homo sapiens	L-cystathionine + H2S	-	r

Subunits

Subunits	Comment	Organism
dimer	-	Homo sapiens

Synonyms

Synonyms	Comment	Organism
CBS	-	Homo sapiens
cystathionine beta-synthase	-	Homo sapiens

Temperature Optimum [°C]

Temperature Optimum [°C]	Temperature Optimum Maximum [°C]	Comment	Organism
37	-	assay at	Homo sapiens

pH Optimum

pH Optimum Minimum	pH Optimum Maximum	Comment	Organism
8.6	-	assay at	Homo sapiens

Cofactor

Cofactor	Comment	Organism	Structure
heme	-	Homo sapiens
pyridoxal 5'-phosphate	-	Homo sapiens
S-adenosyl-L-methionine	-	Homo sapiens

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Release 2023.1 (January 2023)