The crystal structure of a microbial transglutaminase from Streptoverticillium mobaraense has been determined at 2.4 Å resolution. The protein folds into a platelike shape, and has one deep cleft at the edge of the molecule. Its overall structure is completely different from that of the factor XIII-like transglutaminase, which possesses a cysteine protease-like catalytic triad. superimpose well on the catalytic triad "Cys-HisAsp" of the factor XIII-like transglutaminase, in this order. The secondary structure frameworks around these residues are also similar to each other. These results imply that both transglutaminases are related by convergent evolution; however, the microbial transglutaminase has developed a novel catalytic mechanism specialized for the cross-linking reaction. The structure accounts well for the catalytic mechanism, in which Asp 255 is considered to be enzymatically essential, as well as for the causes of the higher reaction rate, the broader substrate specificity, and the lower deamidation activity of this enzyme.Transglutaminase (TGase 1 ; protein-glutamine ␥-glutamyltransferase, EC 2.3.2.13) catalyzes an acyl transfer reaction in which the ␥-carboxyamide groups of peptide-bound glutamine residues act as the acyl donors. The most common acyl acceptors of TGase are the ⑀-amino groups of lysine residues within peptides or the primary amino groups of some naturally occurring polyamines (1, 2). When lysine residues in proteins serve as acyl acceptors, intermolecular or intramolecular ⑀-(␥-glutamyl)lysine bonds are formed, resulting in the polymerization of proteins.TGases are widely distributed in various organisms, including vertebrates (3-7), invertebrates (8, 9), mollusks (10), plants (11), and microorganisms (12). Among these TGases, the human blood coagulation factor XIII has been most characterized (13)(14)(15)(16)(17)(18). By catalyzing the cross-linking between fibrin molecules, factor XIII forms fibrin clots for hemostasis and heals a wound. The crystal structure of human factor XIII has been determined, revealing that it consists of four domains with a cysteine protease-like active site (19 -22). Many TGases are homologous to human factor XIII and share the common feature of Ca 2ϩ -dependent catalytic activity (3-8). A tissue-type TGase from red sea bream liver (fish-derived TGase (FTG)) is an example of such factor XIII-like TGases and shows 33% sequence homology to human factor XIII (7). The crystal structure of FTG has also been determined (23). The overall and active site structures of FTG are essentially similar to those of human factor XIII.A microbial TGase (MTG) has been isolated from the culture medium of Streptoverticillium sp. S-8112 (24), which has been identified as a variant of Sv. mobaraense. This enzyme is the first TGase obtained from a nonmammalian source. Thus far, few TGases have been identified from microorganisms, particularly from Streptoverticillium species (25). Although the physiological role of MTG is still unknown, this protein is secreted from the cytoplas...

Objective: We compared the benefits of sorafenib therapy with continued transarterial chemoembolization (TACE) in TACE-refractory patients with intermediate-stage hepatocellular carcinoma (HCC). Methods: This retrospective study reviewed intermediate-stage HCC patients who underwent the first TACE. Patients were defined as TACE-refractory and divided into two cohorts: (1) patients who switched from TACE to sorafenib and (2) those who continued TACE. We evaluated the patient overall survival (OS) and time to disease progression (TTDP; the time patients reached Child-Pugh C or developed advanced-stage HCC). Results: A total of 509 patients with HCC underwent TACE. Of 249 intermediate-stage HCC patients undergoing the first TACE, 122 were deemed refractory. At the time they were identified as refractory, 20 patients converted to sorafenib, whereas 36 patients continued TACE. We excluded patients with Child-Pugh scores of ≥8, those with advanced-stage HCC, those who had undergone hepatic arterial infusion chemotherapy or other systemic therapy, and those treated with best supportive care alone. The median TTDP and OS were 22.3 and 25.4 months, respectively, in the conversion group, and 7.7 and 11.5 months, respectively, in the continued group (p = 0.001 and p = 0.003, respectively). Conclusions: It is possible that sorafenib conversion might prolong OS and TTDP in TACE-refractory patients with intermediate-stage HCC.

Sorafenib is an orally active multikinase inhibitor that targets serine and threonine, and tyrosine kinases that are involved in tumor-cell signal transduction and tumor angiogenesis. This phase I trial was conducted to evaluate the pharmacokinetics (PK), safety, and preliminary efficacy of sorafenib in Japanese patients with hepatocellular carcinoma (HCC) with underlying liver dysfunction. Patients with unresectable HCC, Child-Pugh status A or B, and adequate organ functions were treated. A single dose of sorafenib was administered, followed by a 7-day wash-out period, after which patients received either sorafenib 200 mg (cohort 1) or 400 mg (cohort 2) twice daily. The PK were investigated after a single dose and during steady state. The efficacy was evaluated using the Response Evaluation Criteria in Solid Tumors. A total of 27 patients were evaluated for PK, safety, and efficacy. Although both area under the concentration-time curve for 0-12 h and maximal concentration at steady state were slightly lower in Child-Pugh B patients than in Child-Pugh A patients, the difference was not considered to be clinically relevant. Common adverse drug events included elevated lipase, amylase, rash or desquamation, diarrhea, and hand-foot skin reaction. A dose-limiting toxicity of hand-foot skin reaction was observed in one patient (cohort 2). Among the 24 patients evaluable for tumor response, one patient (4%) achieved a partial response, 20 (83%) had stable disease, and three (13%) had progressive disease. Sorafenib demonstrated a favorable tolerability and safety profile in Japanese HCC patients. Moreover, promising preliminary antitumor activity has been observed. Finally, there were no clinically relevant differences in PK between Child-Pugh A and B patients. (Cancer Sci 2008; 99: 159-165)

Human serum albumin (HSA) exists in both reduced and oxidized forms, and the percentage of oxidized albumin increases in several diseases. However, little is known regarding the pathophysiological significance of oxidation due to poor characterization of the precise structural and functional properties of oxidized HSA. Here, we characterize both the structural and functional differences between reduced and oxidized HSA. Using LC‐ESI‐TOFMS and FTMS analysis, we determined that the major structural change in oxidized HSA in healthy human plasma is a disulfide‐bonded cysteine at the thiol of Cys34 of reduced HSA. Based on this structural information, we prepared standard samples of purified HSA, e.g. nonoxidized (intact purified HSA which mainly exists in reduced form), mildly oxidized and highly oxidized HSA. Using these standards, we demonstrated several differences in functional properties of HSA including protease susceptibility, ligand‐binding affinity and antioxidant activity. From these observations, we conclude that an increased level of oxidized HSA may impair HSA function in a number of pathological conditions.