caa a22 4500 475744624 CHVBK 20180406123509.0 cr unu---uuuuu 170329e20000201xx s 000 0 eng 10.1023/A:1007090818320 doi (NATIONALLICENCE)springer-10.1023/A:1007090818320 Soret Spectroscopic and Molecular Graphic Analysis of Human Semi-β-Hemoglobin Formation [Elektronische Daten] [Fumin Chiu, Gayathri Vasudevan, Adrianna Morris, Melisenda McDonald] The interaction of heme-free α (αo) and heme-containing β (βh) chains of human hemoglobin has been monitored in 0.1 M potassium phosphate buffer, pH 7 or 8, at [5°C. Soret zero and first-derivative spectra were consistent with a uniform association reaction. Stopped-flow investigations demonstrated association rates on the order of 107 M−1 s−1. This was 100-fold more rapid than the reported rate of combination of αh and βh proteins. This encounter-like rate of semi-β-hemoglobin (αoβh) formation was increased by raising the pH from 7 to 8. pH change is known to affect the spatial arrangement of AB—GH helical entities. Molecular graphic analysis of modeled αo protein superimposed over native αh protein revealed an apo Mb-like structure with well-defined AB—GH segments. Repositioning of these core helical segments, resulting in increased conformational freedom of the α1β1 interface, was apparently responsible for the enhanced association properties of the αo protein. Plenum Publishing Corporation, 2000 Protein—protein interactions nationallicence association kinetics nationallicence encounter rate nationallicence structural superposition nationallicence Chiu Fumin Biochemistry Program, Department of Chemistry, University of Massachusetts Lowell, 01854, Lowell, Massachusetts aut Vasudevan Gayathri Biochemistry Program, Department of Chemistry, University of Massachusetts Lowell, 01854, Lowell, Massachusetts aut Morris Adrianna Biochemistry Program, Department of Chemistry, University of Massachusetts Lowell, 01854, Lowell, Massachusetts aut McDonald Melisenda Biochemistry Program, Department of Chemistry, University of Massachusetts Lowell, 01854, Lowell, Massachusetts aut Journal of Protein Chemistry Kluwer Academic Publishers-Plenum Publishers 19/2(2000-02-01), 157-162 0277-8033 19:2<157 2000 19 10930 https://doi.org/10.1023/A:1007090818320 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1007090818320 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Chiu Fumin Biochemistry Program, Department of Chemistry, University of Massachusetts Lowell, 01854, Lowell, Massachusetts aut NATIONALLICENCE 700 1- Vasudevan Gayathri Biochemistry Program, Department of Chemistry, University of Massachusetts Lowell, 01854, Lowell, Massachusetts aut NATIONALLICENCE 700 1- Morris Adrianna Biochemistry Program, Department of Chemistry, University of Massachusetts Lowell, 01854, Lowell, Massachusetts aut NATIONALLICENCE 700 1- McDonald Melisenda Biochemistry Program, Department of Chemistry, University of Massachusetts Lowell, 01854, Lowell, Massachusetts aut NATIONALLICENCE 773 0- Journal of Protein Chemistry Kluwer Academic Publishers-Plenum Publishers 19/2(2000-02-01), 157-162 0277-8033 19:2<157 2000 19 10930 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer