Abstract
Parvalbumin from anaerobic white skeletal muscle of striped bass (Morone saxatilis) was characterized and the hypothesis tested that parvalbumin concentration varies with body size and thermal acclimation. Two parvalbumin isotypes (molecular weights 8.7 and 10.3 kDa, with pIs of 4.63 and 4.90, respectively) were identified from whole‐muscle extracts by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE), immunoblotting with a monoclonal antibody specific for parvalbumin, and two‐dimensional PAGE of heat‐treated supernatants. Total concentrations of parvalbumin were exceptionally high, ranging from 5.2 to 12.3 mg·g^−1^ wet wt. or 0.55 to 1.29 millimoles per kg wet wt. of tissue. There was a significant inverse relationship between body size and total parvalbumin titer in white muscle (r = −0.89, P < .001), with small fish (<500 g body weight) having twofold more parvalbumin than large fish (>2 kg). However, only concentration of the 8.7 kDa isotype varied between animals of different size. Given that parvalbumin can bind two calcium ions with high affinity, the higher titer of parvalbumin in muscles of small fish may be partially responsible for a higher tail‐beat frequency and faster rate of muscle relaxation than in larger animals. Lower titers of parvalbumin also may prolong the active state of muscle contraction in large striped bass and promote higher muscle force production than in small animals. In contrast to the effects of body size on parvalbumin content, thermal acclimation at cold termperature (5°C) for 8–10 weeks did not change the concentration of parvalbumin in white muscle. © 1995 Wiley‐Liss, Inc.