Influence of osmolytes, thin filaments, and solubility state on elasmobranch phosphofructokinase in vitro

✍ Scribed by Hand, Steven C. ;Somero, George N.

• Publisher: John Wiley and Sons
• Year: 1984
• Tongue: English
• Weight: 509 KB
• Volume: 231
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1402310216

✦ Synopsis

Skeletal muscle phosphofructokinase (PFK) purified from the thornback ray is rapidly inactivated by urea concentrations as low as 50 mM at pH values below 7.0. Urea-induced loss of PFK activity is not offset by trimethylamine-N-oxide. Protection against urea-inactivation in vivo, where urea concentration may approach 0.5 M, may be due to two effects. Filamentous (F) actin and muscle thin filaments moderately reduce the urea-induced loss of PFK activity. The binding of PFK to F-actin and to thin filaments is shown by ultracentrifugation experiments. PFK activity in vivo also may be stabilized in this species by the formation of a particulate enzyme form which is totally resistant to inactivation by physiological concentrations of urea.