A role of heme side-chains of human hemoglobin in its function revealed by circular dichroism and resonance Raman spectroscopy
Structural changes of heme side-chains of human adult hemoglobin (Hb A) upon ligand (O2 or CO) dissociation have been studied by circular dichroism (CD) and resonance Raman (RR) spectroscopies. We point out the occurrence of appreciable deformation of heme side-chains like vinyl and propionate groups prior to the out-of-plane displacement of heme iron. Referring to the recent fine resolved crystal structure of Hb A, the deformations of heme side-chains take place only in the β subunits. However, these changes are not observed in the isolated β chain (β4 homotetramer) and, therefore, are associated with the α–β inter-subunit interactions. For the communications between α and β subunits in Hb A regarding signals of ligand dissociation, possible routes are proposed on the basis of the time-resolved absorption, CD, MCD (magnetic CD), and RR spectroscopies. Our finding of the movements of heme side-chains would serve as one of the clues to solve the cooperative O2 binding mechanism of Hb A.
KeywordsHuman hemoglobin Subunits interactions Circular dichroism Resonance Raman Deformations of heme side-chains Cooperative oxygen binding
We are grateful to the Japanese Red Cross Kanto-Koshinetsu Block Blood Center for the gift of concentrated red cells to advance this human hemoglobin study. This study was supported by a Grant-in-Aid from the Ministry of Education, Culture, Sports, Science, and Technology for Scientific Research (C) to S.N. (17K05606) and Scientific Research (B) to T.K. (24350086), and also by a research grant from the Research Center for Micro-Nano Technology, Hosei University to M.N. and N.M.
Compliance with ethical standards
Conflict of interest
Masako Nagai declares that she has no conflict of interest. Naoki Mizusawa declares that he has no conflict of interest. Teizo Kitagawa declares that he has no conflict of interest. Shigenori Nagatomo declares that he has no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
- Aki-Jin Y, Nagai Y, Imai K, Nagai M (2007) Changes of near-UV circular dichroism spectra of human hemoglobin upon the R → T quaternary structure transition. In: Kneipp K, Aroca R, Kneipp H, Wentrup-Byrne E (eds) New approaches in biomedical spectroscopy, ACS symposium series, vol. 963, chapter 19. American Chemical Society, Washington, DC, pp 297–311CrossRefGoogle Scholar
- Balakrishnan G, Tsai C-H, Wu Q, Case MA, Pevsner A, McLendon GL, Ho C, Spiro TG (2004b) Hemoglobin site-mutants reveal dynamical role of interhelical H-bonds in the allosteric pathway: time-resolved UV resonance Raman evidence for intra-dimer coupling. J Mol Biol 340:857–668CrossRefPubMedGoogle Scholar
- Bunn HF, Forget BG (1986) Hemoglobin: molecular, genetic and clinical aspects. W. B. Saunders Company, PhiladelphiaGoogle Scholar
- Dickerson RE, Geis I (1983) Hemoglobin: structure, function, evolution, and pathology. Benjamin/Cummings, Menlo ParkGoogle Scholar
- Imai K (1982) Allosteric effects in haemoglobin. Cambridge University Press, CambridgeGoogle Scholar
- Jones EM, Monza E, Balakrishnan G, Blouin GC, Mak PJ, Zhu Q, Kincaid JR, Guallar V, Spiro TG (2014) Differential control of heme reactivity in alpha and beta subunits of hemoglobin: a combined Raman spectroscopic and computational study. J Am Chem Soc 136:10325–10339CrossRefPubMedPubMedCentralGoogle Scholar
- Kavanaugh JS, Rogers PH, Arnone A, Hui HL, Wierzba A, DeYoung A, Kwiatkowski LD, Noble RW, Juszczak LJ, Peterson ES, Friedman JM (2005) Intersubunit interactions associated with Tyr42α stabilize the quaternary-T tetramer but are not major quaternary constraints in deoxyhemoglobin. Biochemistry 44:3806–3820CrossRefPubMedGoogle Scholar
- Nagai M, Nagai Y (2011) Studies on hemoglobin quaternary structure transition and heme orientation by circular dichroism. In: Nagai M (ed) Hemoglobin: recent developments and topics. Research Signpost, Kerala, pp 63–77Google Scholar
- Nagatomo S, Nagai M, Kitagawa T (2011) Resonance Raman investigation of quaternary structure change in hemoglobin upon ligand binding. In: Nagai M (ed) Hemoglobin: recent developments and topics. Research Signpost, Kerala, pp 37–61Google Scholar
- Tsubaki M, Srivastava RB, Yu N-T (1982) Resonance Raman investigation of carbon monoxide bonding in (carbon monoxy)hemoglobin and -myoglobin: detection of Fe-CO stretching and Fe-C-O bending vibrations and influence of the quaternary structure change. Biochemistry 21:1132–1140CrossRefPubMedGoogle Scholar