title: Disruption of secondary structure by oxidative stress alters the cross-linking pattern of myosin by microbial transglutaminase.
abstract: Porcine myofibrillar protein (MP) was oxidatively stressed in an iron-H2O2 radical-producing system then subjected to microbial transglutaminase (TGase, E:S=1:20) at 4°C. Changes in the MP secondary structure and cross-linking site on myosin (subfragments S1, S2, rod, light meromyosin, and heavy meromyosin) after TGase treatment were investigated. Circular dichroism and FTIR recorded unraveling of helixes caused by both oxidation and TGase. The loss of α-helix due to TGase treatment was oxidation-dependent, namely, mild oxidation (0.1-1mM H2O2)>non-oxidation>moderate oxidation (5-20mM H2O2). Moreover, oxidation altered the myosin cross-linking pattern: TGase-initiated S1 cross-linking (which dominated non-oxidized MP) partially shifted to the rod under 0.1-0.5mM H2O2 and extensively to the S2 site with 20mM H2O2. Unraveling of the helical structure and formation of disulfide bonds due to oxidation were implicated in the altered myosin cross-linking pattern during subsequent TGase reactions.
authors.affiliation: College of Food Science, Shenyang Agricultural University, Shenyang, Liaoning 110866, China; Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, China.
authors.forename: Chunqiang
authors.initials: C
authors.lastname: Li
authors.affiliation: Department of Animal and Food Sciences, University of Kentucky, Lexington, KY 40546, USA. Electronic address: ylxiong@uky.edu.
authors.forename: Youling L
authors.initials: YL
authors.lastname: Xiong
mesh_terms: D000818:Animals; D002918:Chymotrypsin / Q000378:metabolism; D002942:Circular Dichroism; D004591:Electrophoresis, Polyacrylamide Gel; D005511:Food Handling; D006861:Hydrogen Peroxide / Q000378:metabolism; D008460:Meat / Q000032:analysis; D018482:Muscle, Skeletal / Q000378:metabolism; D009210:Myofibrils / Q000737:chemistry; D009218:Myosins / Q000737:chemistry*; D018384:Oxidative Stress; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared; D013552:Swine; D011503:Transglutaminases / Q000378:metabolism*
chemical_list: D006861:Hydrogen Peroxide; D011503:Transglutaminases; D002918:Chymotrypsin; D009218:Myosins
keywords: Acrylamide (CID: 6579); Ascorbic acid (CID: 54670067); Cross-linking; Ferric chloride (CID: 24380); Myofibrillar protein; N-ethylmaleimide (CID: 4362); Propyl gallate (CID: 4947); Protein oxidation; Transglutaminase; β-Mercaptoethanol (CID: 1567)