Ultraviolet-induced vanadate-dependent modification and cleavage of skeletal myosin subfragment 1 heavy chain. 2. Oxidation of serine in the 23-kDa NH/sub 2/-terminal tryptic peptide

Journal Article · Tue Nov 01 00:00:00 EST 1988 · Biochemistry; (United States)

OSTI ID:5980349

Cremo, C R; Grammer, J C; Yount, R G

Myosin subfragment 1 (S1) can be specifically photomodified at the active site without polypeptide chain cleavage by irradiating the stable MgADP-orthovanadate-S1 complex with UV light above 300 nm. Here, the UV spectral properties of photomodified S1 were used to determined the nature and location of the photomodified residue(s) within S1. By comparison of the unusual pH dependence of the UV absorption spectrum of the photomodified S1 to that of the S1-MgADP-V/sub i/ complex as a control the photomodified residue(s) was (were) localized to the 23-kDa NH/sub 2/-terminal tryptic peptide of the heavy chain. NaBH/sub 4/ reduced the photomodified S1, but not the control, to regenerate the original spectral properties and ATPase activities of the unmodified S1. Amino acid analysis of photomodified S1 reduced with NaB/sup 3/H/sub 4/ gave only (/sup 3/H)serine, suggesting the hydroxyl group of serine had been oxidized to a serine aldehyde. The pH dependence of the absorption spectrum of the photomodified enzyme can be explained by an equilibrium between a chromophoric enolate anion of the serine aldehyde (favored in base) and less chromophoric keto and enol forms (favored in acid). The oxidized serine(s) was (were) shown to be directly involved with the vanadate-dependent photocleavage of the S1 heavy chain previously described by Grammer et al. (1988). This serine(s) is (are) likely to be important to the binding and hydrolysis of the ..gamma..-PO/sub 4/ of ATP at the active site of S1.

• Research Organization: Washington State Univ., Pullman (USA)
• OSTI ID: 5980349
• Journal Information: Biochemistry; (United States), Vol. 27:22
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
MYOSIN
BIOLOGICAL RADIATION EFFECTS
SERINE
OXIDATION
ABSORPTION SPECTRA
ATP
EXTREME ULTRAVIOLET RADIATION
PEPTIDES
PH VALUE
TRITIUM COMPOUNDS
ULTRAVIOLET SPECTRA
VANADATES
AMINO ACIDS
BIOLOGICAL EFFECTS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
ELECTROMAGNETIC RADIATION
GLOBULINS
HYDROXY ACIDS
LABELLED COMPOUNDS
NUCLEOTIDES
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PROTEINS
RADIATION EFFECTS
RADIATIONS
SPECTRA
TRANSITION ELEMENT COMPOUNDS
ULTRAVIOLET RADIATION
VANADIUM COMPOUNDS
550602* - Medicine- External Radiation in Diagnostics- (1980-)