MUTANT ACCESSION NUMBER: 61
PROTEIN NAME: Serine hydroxymethyltransferase, cytosolic (EC 2.1.2.1) (Serine methylase) (Glycine hydroxymethyltransferase) (SHMT).
SWISS PROT ENTRY:
GLYC_SHEEP
ORGANISM: OVIS ARIES SHEEP
GENE NAME: SHMT1
VARIANT OR MUTAGEN:Mutagen
PMD ENTRY: A993462
MUTATIONS:
POINT Asp 89 Asn
EFFECTS: Secondary structure [=] (by far-UV CD spectrum): When purified
in the presence of PLP, the D89N SHTM is a mixture of dimers
and tetramers with the proportion of tetramers increasing with
an increase in PLP concentration used during purification.
(The wild-type SHTM is purified as a tetramer.): The apo-form
of the D89N SHTM is a dimer unlike the apo-form of the wild-
type SHTM which is present predominantly as a tetramer.: The
apo mutant dimer can not be reconstituted to the holo-form by
the addition of excess of PLP.
FUNCTION Specific activity of the D89N dimer in the absence of PLP [-]
and in the presence of PLP [-]: Formation of the quinonoid
spectral intermediate in the reaction of the D89N dimer with
glycine and H4-folate [0]: Specific activity of the D89N
tetramer in the absence of PLP [-] and in the presence of PLP
[=]: For the D89N tetramer, Km [=], kcat [-] and kcat/Km [-]
for serine in the absence of PLP: For the D89N tetramer,
Km [=], kcat [=] and kcat/Km [=] for serine in the presence of
PLP: Formation of the quinonoid spectral intermediate in the
reaction of the D89N tetramer with glycine and H4-folate [-]
STABILITY Thermal stability of D89N tetramer in the presence of PLP [-]
(as indicated by Tm): Thermal stability of the D89N tetramer
is markedly increased by addition of serine, as in the case of
the wild-type SHTM.: There is no change in the thermal
stability of the D89N dimer in the presence and absence of
serine.
REFERENCE:
PUBMED ID:
10493937
TITLE:Asp-89: a critical residue in maintaining the oligomeric structure of sheep liver cytosolic serine hydroxymethyltransferase
AUTHOR:Krishna Rao JV, Jagath JR, Sharma B, Appaji Rao N, Savithri HS.
REFERENCE:Biochem J. 1999 Oct 1;343 Pt 1:257-63.
3D STRUCTURE: Null
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