Details

Autor(en) / Beteiligte

• Bivin, Donald B.
• Ue, Kathleen
• Khoroshev, Mikhail
• Morales, Manuel F.

Titel

Effect of Lysine Methylation and Other ATPase Modulators on the Active Site of Myosin Subfragment 1

Ist Teil von

• Proceedings of the National Academy of Sciences - PNAS, 1994-08, Vol.91 (18), p.8665-8669

Ort / Verlag

United States: National Academy of Sciences of the United States of America

Erscheinungsjahr

1994

Quelle

MEDLINE

Beschreibungen/Notizen

• Many and diverse modifications of the myosin subfragment 1 (S-1) increase (modulate) its ATPase activity, including interaction of this particle with actin; a recent addition to these modifications is the extensive lysine modification of S-1 that seems prerequisite to crystallizing it for structure analysis. In this study we first established kinetically the ATPase modulations induced by various treatments of the myosin S-1 enzyme, and we also measured two properties of the S-1 active site-the affinity with which the site binds (a fluorescent analog of) the enzymatic nucleotide product and the access that a fluorescence quencher has to the bound ADP product-in an effort to get at the mechanism of modulation. Modulations achieved by substituting Ca2+for the normal Mg2+cocatalyst or by substituting Cl-for the normal carboxylate anion seem due to the product being held more loosely by the modulated enzyme. In other illustrative modulations (lysine methylation, or alkylation of Cys-707, or transition from neutral pH to pH 9.2) nucleotide product affinity and access to quencher do change, but not in a pattern explained simply by a lifting of product inhibition. Lysine methylation results in weaker binding of nucleotide product.