Chemical modification of the sole histidine residue of smooth muscle caldesmon

FEBS Letters

Bonet-Kerrache, Armelle A.¹  Walsh, Michael P.¹ 

[1] Department of Medical Biochemistry, University of Calgary, Calgary, Alberta, T2N 4N1 Canada

关键词: Caldesmon;    Calmodulin;    Chemical modification;    Smooth muscle;   

DOI  :  10.1016/0014-5793(91)80363-8

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Caldesmon was stoichiometrically N-carbethoxylated specifically at the only histidine residue (His-610) with diethylpyrocarbonate. Carbethoxylation of a 1:1 molar complex of caldesmon and calmodulin in the presence of Ca²⁺ resulted in the stoichiometric N-carbethoxylation of His-610 of caldesmon and His-107 of calmodulin. Carbethoxy-caldesmon, like the unmodified protein, bound to immobilized calmodulin (in the presence of Ca²⁺) and to immobilized tropomyosin (at low ionic strength). The affinity of F-actin for carbethoxy-caldesmon (K ₄ = 1.29 × 10⁻⁴M) was similar to that for unmodified caldesmon (K ₄ = 0.88 × 10⁻⁴M), and the modified protein was as effective as control caldesmon in the inhibition of the actin-activated MgATPase of skeletal muscle myosin. We conclude that the predicted basic amphiphilic α-helical sequence (Arg-593-His-610) does not represent the calmodulin-binding site of caldesmon. Furthermore, His-610 does not play a major role in the interaction of caldesmon with F-actin or tropomyosin.

【 授权许可】

Unknown