Marcos Crupkin

Electron microscopical and biochemical studies of actomyosin from pre- and post-spawned hake

Abstract 1. 1. The ultrastructure of actomyosin obtained from pre- and post-spawned hake was investigated. 2. 2. A characteristic arrowhead structure was found on actomyosin filaments obtained from post-spawned hake. 3. 3. The protein obtained from pre-spawned fish showed a loss of the filamentous structure. 4. 4. The loss of the filamentous structure in actomyosin from pre-spawned hake was related to a decreased affinity between myosin and actin.

Action of Triton X-100 on the biochemical and functional properties of hake (Merluccius hubbsi) myofibrils

Abstract 1. 1. The effects of Triton X-100 on the kinetic of Mg2+-ATPase and the functional properties of hake myofibrils were investigated. 2. 2. Triton X-100 increased the Hill coefficient to 1.5 in an allosteric type of reaction for the myofibrillar Mg2+-ATPase. 3. 3. Triton X-100 reduced the viscosity and the ATP response of myosin B and changed the contractile response of myofibrils. 4. 4. These changes would be due to the action of Triton X-100 on actin-myosin interacting sites.

Influence of the Capture Method on the Physicochemical and Functional Properties of Myofibrillar Proteins of Fin from Frozen, Stored Squid (Illex argentinus)

ABSTRACT n The physicochemical and functional properties of actomyosin from fins of frozen, stored squid caught either by jigging machines (AME1) or by trawling (AME2) were investigated. At time 0 SDS-PAGE, 10% of AMEl and AME2 showed the characteristic polypeptide bands of myofibrillar proteins and two components of 155 kDa and 55 kDa. Both the degradation of the myosin heavy chain and an increase in the 155-kDa component occurred earlier in AME2. Irrespective of the capture method used, no significant changes in protein solubility and a decrease (P < 0.05) in reduced viscosity were observed in both AMEl and AME2. Surface hydrophobicity (SoANS) of AMEl increased (P < 0.05) during the first month of storage and remained unchanged thereafter. The SoANS of AME2 was unchanged. The initial value of SoANS of AME2 was higher than that of AMEl. The emulsion activity index and the emulsion stability of AME2 increased (P < 0.05) during the first month of storage, whereas the emulsion activity index and emulsion stability of AMEl remained unchanged during the frozen storage period. These results indicate that the capture method influences the rate of autolysis and the functional properties of myofibrillar proteins of fin from frozen, stored squid.

Incorporation of 32P during early amphibian embryogenesis

Abstract 1. 1. The incorporation of 32 P during early embryogenesis was surveyed and a comparative study was made with neural phosphoproteins. 2. 2. In oocytes and in blastulas 90 per cent of the 32 P was incorporated into the acid-soluble fraction and 4 per cent into phosphoproteins. 3. 3. An increase of incorporation into phospholipids was found from oocyte (1·5 per cent) to blastula (4·5 per cent). Since this level did not change a 64 per cent rise in specific radioactivity was observed. 4. 4. The high content of phosphoprotein in the egg and blastula contrasted with a low level in the retina and brain. However, the specific radioactivity in the retina and brain was seven and sixteen times higher respectively than that in the unfertilized oocyte.