PMID- 10052942
OWN - NLM
STAT- MEDLINE
DCOM- 19990322
LR  - 20131121
IS  - 0006-2960 (Print)
IS  - 0006-2960 (Linking)
VI  - 38
IP  - 9
DP  - 1999 Mar 2
TI  - Binding of pyridoxal 5'-phosphate to the heme protein human cystathionine
      beta-synthase.
PG  - 2716-24
AB  - Cystathionine beta-synthase (CBS), a pyridoxal 5'-phosphate (PLP) dependent
      enzyme, catalyzes the condensation of serine and homocysteine to form
      cystathionine. Mammalian CBS was recently shown to be a heme protein. While the
      role of heme in CBS is unknown, catalysis by CBS can be explained solely by
      participation of PLP in the reaction mechanism. In this study, treatment of CBS
      with sodium borohydride selectively reduced the Schiff base but did not affect
      the heme. Purification and sequencing of the PLP-cross-linked peptide from a
      trypsin digest of the reduced enzyme revealed the evolutionarily conserved Lys119
      to be the residue forming the Schiff base. Serine and hydroxylamine form an
      alpha-aminoacrylate and an oxime with PLP in CBS, respectively. The
      sulfhydryl-containing substrate, homocysteine, disturbs the heme environment but 
      does not interact with PLP. In contrast to other PLP-dependent enzymes, CBS emits
      no PLP-related fluorescence when excited at 296 or 330 nm. PLP but not heme
      dissociates from the enzyme in the presence of hydroxylamine. The dissociation of
      PLP is a multistage process involving a short approximately 500 s lag phase,
      followed by a rapid inactivation and a slower PLP-oxime formation. PLP-free CBS
      exhibits a decrease of secondary structure as well as loss of CBS activity that
      can be only partially restored by PLP. This study constitutes the first
      comprehensive investigation of PLP interaction with a heme protein.
FAU - Kery, V
AU  - Kery V
AD  - Department of Pediatrics, University of Colorado School of Medicine, Denver
      80262, USA.
FAU - Poneleit, L
AU  - Poneleit L
FAU - Meyer, J D
AU  - Meyer JD
FAU - Manning, M C
AU  - Manning MC
FAU - Kraus, J P
AU  - Kraus JP
LA  - eng
GR  - P01HD08315/HD/NICHD NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Biochemistry
JT  - Biochemistry
JID - 0370623
RN  - 0 (Borohydrides)
RN  - 0 (Hemeproteins)
RN  - 0 (Imines)
RN  - 0 (Oximes)
RN  - 0 (Recombinant Proteins)
RN  - 2FP81O2L9Z (Hydroxylamine)
RN  - 5V5IOJ8338 (Pyridoxal Phosphate)
RN  - 87L0B9CPPA (sodium borohydride)
RN  - EC 4.2.1.22 (Cystathionine beta-Synthase)
RN  - K3Z4F929H6 (Lysine)
SB  - IM
MH  - Binding Sites/drug effects
MH  - Borohydrides/chemistry
MH  - Cystathionine beta-Synthase/*chemistry/genetics/metabolism
MH  - Enzyme Activation
MH  - Hemeproteins/*chemistry/metabolism
MH  - Humans
MH  - Hydroxylamine/metabolism/pharmacology
MH  - Imines/metabolism
MH  - Lysine/metabolism
MH  - Oxidation-Reduction
MH  - Oximes/metabolism
MH  - Pyridoxal Phosphate/*chemistry/metabolism
MH  - Recombinant Proteins/chemistry/metabolism
MH  - Substrate Specificity
EDAT- 1999/03/03 00:00
MHDA- 1999/03/03 00:01
CRDT- 1999/03/03 00:00
PHST- 1999/03/03 00:00 [pubmed]
PHST- 1999/03/03 00:01 [medline]
PHST- 1999/03/03 00:00 [entrez]
AID - 10.1021/bi981808n [doi]
AID - bi981808n [pii]
PST - ppublish
SO  - Biochemistry. 1999 Mar 2;38(9):2716-24. doi: 10.1021/bi981808n.