Uncontrolled bleeding following trauma is associated with a high risk of death. Here, an emerging kaolinite nanoclay composite (iron oxide-kaolinite, α-Fe 2 O 3 -kaolin KAc ) is developed, based on the natural hemostat hematitum used in traditional Chinese medicine to effectively control hemorrhage. α-Fe 2 O 3 -kaolin KAc stops bleeding in ≈183 ± 16 s and exhibits higher hemostatic activity than the related compounds FeOOH-kaolin KAc (298 ± 14 s), γ-Fe 2 O 3 -kaolin KAc (212 ± 11 s), and Fe 3 O 4 -kaolin KAc (218 ± 15 s). This rapid effect is attributed to efficient absorption of the fluid in blood, activation of blood platelets, and induction of the coagulation cascade by kaolinite and the aggregation of red blood cells induced by α-Fe 2 O 3 . α-Fe 2 O 3 -kaolin KAc shows slight hemolysis (<0.11%) as compared to kaolinite (30%), which accelerates wound healing. The biocompatibility, hemostatic activity, and low cost of α-Fe 2 O 3 -kaolin KAc make it a safe and effective agent for preventing massive blood loss after traumatic injury.

No abstract

No abstract

No abstract

A soluble hydrogenase from Allochromatium vinosum was purified. It consisted of a large (M (r) = 52 kDa) and a small (M (r) = 23 kDa) subunit. The genes encoding for both subunits were identified. They belong to an open reading frame where they are preceded by three more genes. A DNA fragment containing all five genes was cloned and sequenced. The deduced amino acid sequences of the products characterized the complex as a member of the HoxEFUYH type of [NiFe] hydrogenases. Detailed sequence analyses revealed binding sites for eight Fe-S clusters, three [2Fe-2S] clusters and five [4Fe-4S] clusters, six of which are also present in homologous subunits of [FeFe] hydrogenases and NADH:ubiquione oxidoreductases (complex I). This makes the HoxEFUYH type of hydrogenases the one that is evolutionary closest to complex I. The relative positions of six of the potential Fe-S clusters are predicted on the basis of the X-ray structures of the Clostridium pasteurianum [FeFe] hydrogenase I and the hydrophilic domain of complex I from Thermus thermophilus. Although the HoxF subunit contains binding sites for flavin mononucleotide and NAD(H), cell-free extracts of A. vinosum did not catalyse a H(2)-dependent reduction of NAD(+). Only the hydrogenase module (HoxYH) could be purified. Its electron paramagnetic resonance (EPR) and IR spectral properties showed the presence of a Ni-Fe active site and a [4Fe-4S] cluster. Its activity was sensitive to carbon monoxide. No EPR signals from a light-sensitive Ni(a)-C* state could be observed. This study presents the first IR spectroscopic data on the HoxYH module of a HoxEFUYH type of [NiFe] hydrogenase.