Peptide mapping of polymorphic myosin heavy chain isoforms in different muscle types of some freshwater teleosts

Abstract

A modified SDS-PAGE system has been employed to resolve polymorphic myosin heavy chain (MyHC) isoforms in different muscle types of three freshwater teleosts displaying different modes of respiration, adaptive features and life styles. Investigated species include accessory air-breather Channa punctata along with exclusive aquatic breather major carps Labeo rohita and Catla catla. All the selected species show specificity and expressivity of at least three MyHC isoforms, one each in red, head and pectoral muscles. Chymotryptic peptide maps unambiguously support substructural individuality of each MyHC isoforms with the type-specific dispersal of chymotryptic cleavage sites. Specific Ca(2+)- and Mg(2+)-ATPase activities of natural actomyosin (NAM) of lateral line red muscle of C. punctata were low and less sensitive to pH, but sensitive to KCl concentrations between 0.05 and 0.15 M. In comparison, the specific enzymatic activities of NAM of red muscle from the carps (L. rohita and C. catla) were substantially high with prominent peaks at pH 7.5 and near insensitivity to 0.05-0.15 M KCl, while C. punctata had shown a different response at these molarities. Thus, the data favor a correlation between breathing modes and life style and the differences in pH or ionic strength sensitivities of ATPases. Unique profiles of peptide maps and the dispersal patterns of hydrophobic residues (cleavage sites of chymotrypsin) in MyHC of different muscle types further reflect individuality of their evolutionary histories.

Biochemical Variations in Salt Soluble Fractions of Ultrasonicated Actomyosin Isolated from Broiler Breast-Muscle

“…ATP binding site is located at the apex of the cleft which separates the two 50 kDa actin binding domains of myosin subfragment-1. [35,36] Our results suggest that low intensity sonication might have affected actin binding domains as well as the ATP binding site. This is supported by the changes in profiles and magnitudes of Ca 2+ -and K + (EDTA)-ATPase activities and actin-myosin interaction indicator, Mg 2+-ATPase.…”

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“…For preparative native PAGE, partially purified and dialyzed Tf samples were loaded on to a wide single slot preparative gel and run according to native PAGE protocol essentially as described above. Band identified as Tf were subsequently cut out and protein was electroeluted as per standard protocol (Nabi et al, 2007;Ahmad and Hasnain, 2013). Electroeluted samples of each Tf electromorph or isoform was crosschecked for homogeneity by native PAGE.…”

“…Previously (Hasnain and Jabeen, 2001;Ahmad and Hasnain, 2006). LDH isozymes, myofibrillar proteins and polymorphic myosin heavy chain of channids also exhibit functional plasticity (Ahmad and Hasnain, 2005;Arif et al, 2007;Ahmad, 2009;Ahmad and Hasnain, 2013). While other fishes may temporarily switch on to expression of heat shock proteins (Kayhan and Duman, 2010), thermostability of proteins appears to be inherent characteristic of airbreathing channids (Hasnain and Jabeen, 2001;Ahmad et al, 2007a;Arif et al, 2007).…”