caa a22 4500 463156293 CHVBK 20180406164735.0 cr unu---uuuuu 170326e20070901xx s 000 0 eng 10.1007/s00217-006-0458-y doi (NATIONALLICENCE)springer-10.1007/s00217-006-0458-y Time-dependent nature in peptic hydrolysis of native bovine hemoglobin [Elektronische Daten] [Rong-Xin Su, Wei Qi, Zhi-Min He] Native bovine hemoglobin was digested with pepsin at pH 4.5 in a batched stirred tank reactor. The resulting peptides in the time-course samples were separated and identified by RP-HPLC coupled with ESI-MS/MS. The secondary structure of bovine hemoglobin was not significantly changed after acid-treatment at pH 4.5 based on far-UV circular dichroism spectra. The α-helix contents of peptic hydrolysates decreased gradually with time according to ‘one-by-one' mechanism. MS/MS analysis enabled unambiguous identification of 31 and 15 peptides released respectively from α-chain and β-chain, which resulted in their sequence coverage of 100 and 76%. The discrimination of peptic susceptibility between different protein areas was compared in terms of the time-dependent release of peptides. At first, peptic cleavage sites were concentrated around N- and C-terminal regions of α-chain and β-chain. Later, pepsin hydrolyzed the middle part of α-chain from N- to C-terminal, while little enzymatic cleavage occurred in the center region of β-chain due mainly to their high hydrophilic nature. The release kinetics of peptides was discussed in relation to the hydrophobicity of amino acid residues of polypeptide chains. Springer-Verlag, 2006 Hemoglobin nationallicence Pepsin nationallicence Protein hydrolysis nationallicence Enzymatic kinetics nationallicence Tandem mass spectrometry nationallicence Circular dichroism nationallicence Su Rong-Xin Chemical Engineering Research Center, School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, People's Republic of China aut Qi Wei Chemical Engineering Research Center, School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, People's Republic of China aut He Zhi-Min Chemical Engineering Research Center, School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, People's Republic of China aut European Food Research and Technology Springer-Verlag 225/5-6(2007-09-01), 637-647 1438-2377 225:5-6<637 2007 225 217 https://doi.org/10.1007/s00217-006-0458-y text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00217-006-0458-y text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Su Rong-Xin Chemical Engineering Research Center, School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, People's Republic of China aut NATIONALLICENCE 700 1- Qi Wei Chemical Engineering Research Center, School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, People's Republic of China aut NATIONALLICENCE 700 1- He Zhi-Min Chemical Engineering Research Center, School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, People's Republic of China aut NATIONALLICENCE 773 0- European Food Research and Technology Springer-Verlag 225/5-6(2007-09-01), 637-647 1438-2377 225:5-6<637 2007 225 217 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer