jp8b10077_si_001.pdf (397.56 kB)
Quaternary Structure Analysis of a Hemoglobin Core in Hemoglobin–Albumin Cluster
journal contribution
posted on 2018-11-16, 00:00 authored by Yoshitsugu Morita, Taiga Yamada, Moeka Kureishi, Kiyohito Kihira, Teruyuki KomatsuA core–shell
ensemble of bovine hemoglobin (Hb) and human serum albumin (HSA) is
an artificial O2 carrier as a red blood cell substitute.
This protein particle is created by covalent wrapping of a carbonyl
Hb with HSAs: HbR–HSA3 cluster, where HbR signifies the use of carbonyl Hb (relaxed
(R) state conformation) as a starting material. The HbR–HSA3 cluster exhibits high O2 affinity and low cooperativity. Analysis of the quaternary
structure of the central HbR in the cluster revealed that
its high O2 affinity is attributed to the physically immobile
HbR nucleus. Circular dichroism and UV–vis absorption
spectroscopy showed that the structure of deoxy HbR core
closely resembles the R-state. The crystal structure of Lys-modified
carbonyl HbR was superimposed on that of carbonyl Hb. These
results imply that chemical modifications of the surface Lys groups
and Cys-93(β) of the carbonyl Hb with cross-linking agent interfered
in the quaternary structure movement from the R-state to tense (T)
state. As expected, coupling of deoxy Hb (T-state) with HSAs yielded
HbT–HSA3 cluster having
low O2 affinity. The mixing of HbR–HSA3 and HbT–HSA3 clusters conferred a tailor-made formulation of
artificial O2 carrier with a desired O2 affinity
(P50).