TY - JOUR
T1 - The T-to-R transformation in hemoglobin
T2 - A reevaluation
AU - Srinivasan, Rajgopal
AU - Rose, George D.
PY - 1994/11/8
Y1 - 1994/11/8
N2 - The relationship between the T, R, and R2 quaternary forms of hemoglobin is examined by computational experiments. Contrary to previous suggestions, we propose that the R quaternary form may lie on the pathway from T to R2. This proposal is consistent with four independent observations. (i) Difference distance maps are used to identify those parts of the molecule that undergo conformational change upon oxygenation. The simplest interpretation of these maps brackets R between T and R2. (ii) Linear interpolation from T to R2 passes through R. (iii) The well-known 'switch' region (so called because, upon transition between the T and R quaternary forms, a residue from the β2 subunit toggles between two stable positions within the α1 subunit) progresses from T through R to R2, successively. (iv) A hitherto-undocumented feature, diagnostic of the R structure, is noted within the α subunit: upon transformation from T to R, the β-turns at the amino termini of the E and F helices flip from one turn type to another. Upon transformation from R to R2, the latter turn-a strained conformation-flips back again.
AB - The relationship between the T, R, and R2 quaternary forms of hemoglobin is examined by computational experiments. Contrary to previous suggestions, we propose that the R quaternary form may lie on the pathway from T to R2. This proposal is consistent with four independent observations. (i) Difference distance maps are used to identify those parts of the molecule that undergo conformational change upon oxygenation. The simplest interpretation of these maps brackets R between T and R2. (ii) Linear interpolation from T to R2 passes through R. (iii) The well-known 'switch' region (so called because, upon transition between the T and R quaternary forms, a residue from the β2 subunit toggles between two stable positions within the α1 subunit) progresses from T through R to R2, successively. (iv) A hitherto-undocumented feature, diagnostic of the R structure, is noted within the α subunit: upon transformation from T to R, the β-turns at the amino termini of the E and F helices flip from one turn type to another. Upon transformation from R to R2, the latter turn-a strained conformation-flips back again.
KW - allosteric transitions
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U2 - 10.1073/pnas.91.23.11113
DO - 10.1073/pnas.91.23.11113
M3 - Article
C2 - 7972019
AN - SCOPUS:0027988868
VL - 91
SP - 11113
EP - 11117
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
SN - 0027-8424
IS - 23
ER -