Structural Insights into a Hemoglobin-Albumin Cluster in Aqueous Medium.

A hemoglobin (Hb) wrapped covalently by three human serum albumins (HSAs) is a triangular protein cluster designed as an artificial O2-carrier and red blood cell substitute. We report the structural insights into this Hb-HSA3 cluster in aqueous medium revealed by 3D reconstruction based on cryogenic transmission electron microscopy (cryo-TEM) data and small-angle X-ray scattering (SAXS) measurements. Cryo-TEM observations showed individual particles with approximately 15 nm diameter in the vitrified ice layer. Subsequent image processing and 3D reconstruction proved the expected spatial arrangements of an Hb in the center and three HSAs at the periphery. SAXS measurements demonstrated the monodispersity of the Hb-HSA3 cluster having a molecular mass of 270 kDa. The pair-distance distribution function suggested the existence of oblate-like particles with a maximum dimeter of ∼17 nm. The supramolecular 3D structure reconstructed from the SAXS intensity using an ab initio procedure was similar to that obtained from cryo-TEM data.

Core-shell clusters of human haemoglobin A and human serum albumin: artificial O2-carriers having various O2-affinities.

This report describes the synthesis, structure, and O2-binding properties of core-shell clusters composed of human haemoglobin A (HbA) in the centre and human serum albumin (HSA) at the periphery (HbA-HSAm) as potential O2-carriers designed as red blood cell (RBC) substitutes. Protein clusters were prepared by covalent linkages between HbA lysins and HSA cysteine-34 using a heterobifunctional cross-linker, succinimidyl-4-(N-maleimidomethyl)cyclohexane-1-carboxylate. Major products (m = 2, 3, 4) were isolated using gel filtration chromatography. The low isoelectric points (pI = 5.0-5.2) of the clusters were almost identical to that of HSA, proving the wrapping of HbA by negatively charged HSA. The 3D reconstruction of HbA-HSA3 based on transmission electron microscopy images revealed a complete triangular structure. The proposed geometries enabled us to assign a possible spatial arrangement of the HbA centre and HSA periphery. The HbA-HSAm clusters showed higher O2-affinities (P50 = 8-9 Torr) than the native HbA. The clusters prepared under N2 atmosphere showed a low O2-affinity (P50 = 26 Torr) resembling those of human RBC. Moreover, the cluster containing an αα-cross-linked HbA with bis(3,5-dibromosalicyl)fumarate showed a markedly low O2-affinity (P50 = 35 Torr). These HbA-HSAm clusters with various O2-affinities can support a new generation of RBC substitutes, which can be better tuned to play a role in O2 transport.

Asia-Pacific mussel watch for emerging pollutants: Distribution of synthetic musks and benzotriazole UV stabilizers in Asian and US coastal waters.

We analyzed 68 green and blue mussels collected from Cambodia, China, Hong Kong, India, Indonesia, Japan, Korea, Malaysia, Philippines, Vietnam and the USA during 2003 and 2007, to elucidate the occurrence and widespread distributions of emerging pollutants, synthetic musks and benzotriazole UV stabilizers (BUVSs) in Asia-Pacific coastal waters. Synthetic musks and BUVSs were detected in mussels from all countries, suggesting their ubiquitous contamination and widespread distribution. High concentrations of musks and BUVSs were detected in mussels from Japan and Korea, where the levels were comparable or greater than those of PCBs, DDTs and PBDEs. Significant correlations were found between the concentrations of HHCB and AHTN, and also between the concentrations of UV-327 and UV-328, which suggest similar sources and compositions of these compounds in commercial and industrial products. To our knowledge, this is the first study of large-scale monitoring of synthetic musks and BUVSs in Asia-Pacific coastal waters.

Detection of benzotriazole UV stabilizers in the blubber of marine mammals by gas chromatography-high resolution mass spectrometry (GC-HRMS).

Benzotriazole UV stabilizers (BUVSs), such as UV-328 and UV-327, were identified in the blubbers of finless porpoises (Neophocaena phocaenoides) collected from the Ariake Sea, western Japan, by gas chromatography-high resolution mass spectrometry (GC-HRMS). The mean concentrations and standard deviations of UV-328 and UV-327 in five blubber samples were 38 ± 28 ng g(-1) (lipid wt) and 19 ± 19 ng g(-1), respectively. The bioconcentration factor (BCF) of UV-327 between water and finless porpoises was estimated to be 33 300, which is approximately one order of magnitude higher than that found for small fish inhabiting the same regions. The BCF of UV-327 in finless porpoises was similar to that of persistent organochlorine pesticide, hexachlorocyclohexane (HCH: 37 000) in marine mammals from the western North Pacific Ocean. These results suggest that BUVSs appear to be persistent and bioaccumulative in the aquatic food chain. Further investigations on temporal trends, and regional and global monitoring of BUVSs are needed to understand their environmental profiles and potential risks to wildlife and human.