Thermal aggregation of cod (Gadus morhua) muscle proteins using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide as a zero length cross-linker.

Abstract

The initial stages of thermally-induced aggregation of cod myofibrils resulted from noncovalent intermolecular cross-linking as demonstrated by SDSelectrophoresis. The nature of the noncovalent bonds was studied by introducing a zero length cross-linker, l-ethyl-3-(3-dimethylamino propyl) carbodiimide (EDC). This allowed the examination of the noncovalent interactions by SDS electrophoresis and quantitative densitometry. Initially, during heating, about 50 % of the myosin heavy chain was cross-linked to form a polymerized complex before the involvement of actin, regulatory proteins, or the myosin light chains. Inhibition of thermally-induced noncovalent crosslinking with triglycerides or Triton X-100 as well as the enhancement of aggregation at higher ionic strength, suggested the importance of hydrophobic interaction in this reaction. Cod myosin heavy chains were prepared and the head regions labelled with the fluorescent probe, yV-[7(dimethylamino)-4-methyl-3-coumarinyl] maleimide (DACM)which reacts specifically with two thiol groups near the active sites for Ca2+ and EDTA-ATPase. Chymotryptic cleavage of the thermally aggregated myosin heavy chains suggested the involvement of the tail region of the molecule rather than the head in the noncovalent cross-linking reactions.

Improvement of the gelling ability in restructured fish products: effect of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide level and pH

“…It must be remarked that albeit fitted responses suggest a lower pH value, best experimental data was attained in the 11th run, pH = 4.94 (Table 3). Moreover, results contradict the interpretation given by some authors [31] that the disappearance of protein bands from SDS-PAGE gels of cod myofibrils illustrated protein aggregation and was not function of EDC reactivity. Protein aggregation does not explain, for instance, the GS response as a function of pH.…”

Effects of Thermal Sensitivity of Fish Proteins from Various Species on Rheological Properties of Gels

“…Holding fish muscle proteins, after comminution with salt, at temperatures below 40 "C before a subsequent heating at higher temperatures resulted in an ordered structure of the protein molecules, which consequently produced stronger gels (Lanier and others 1982). Previous studies indicated that myosin was the major protein affecting the gel-forming ability of fish during setting (Gill andConway 1989, Sano andothers 1988). Calcium dependent endogenous TGase was also reported to be responsible for the unique setting ability of surimi (Seki and others 1990; b a t h and others 1992; Lee and others 1997b).…”

A Comparative Study on Physical Properties and Chemical Interactions of Gels From Tilapia Meat Pastes Induced by Heat and Pressure

“…Cheftel and Culioli (1997) reported that a large increase solubilization of myofibrillar proteins was observed when the applying pressures were between 150 and 300 MPa. It would appear virtually certain that for fish proteins, the setting effect uniquely involves non-disulfide cross-linking of myosin (Gill and Conway 1989;Sano et al 1990). The high breaking strain but low breaking force of pressure-induced gels was contributed to constitution of hydrogen bonds, hydrophobic interactions but the small amount of disulfide bonds.…”