PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 3490403

Evidence that a nicked C4b, C4b', is a functionally active C4b derivative.

M Yamazaki·C Ichihara·S Nagasawa
View original source ↗Export metadata ↓

Abstract

Factor I-catalyzed C4b cleavage is a regulatory reaction for the classical pathway of the complement system. Although the reaction was shown to be a two-step reaction, production of a nicked form of C4b, C4b', as an intermediate cleavage product and subsequent splitting of C4b' into C4c and C4d, it is not known which of the two steps represents the inactivation of the C4b function in the assembly of C3 convertase, C4b,2a. We have purified C4b' and assessed the ability of C4b' to assemble C3 convertase with C2 by utilizing size exclusion high performance liquid chromatography. Evidence was obtained demonstrating that C4b' still retains the function of C4b to assemble C3 convertase. Thus, the substantial step for the inactivation of the C4b function appears to be the second cleavage reaction, that is, the cleavage of C4b' into C4c and C4d.

Explore related subjects

CatalysisChromatography, High Pressure LiquidComplement C3-C5 ConvertasesComplement C4Complement C4bHumansJournal ArticleResearch Support, Non-U.S. Gov't

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

M Yamazaki, C Ichihara, S Nagasawa. 1986-11-10. Evidence that a nicked C4b, C4b', is a functionally active C4b derivative.. https://doi.org/10.1016/0014-5793(86)81550-2

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2026

Engineering copper ferrite (CuFe2O4) nanocomposites for enhanced eco-friendly photocatalysis: a systematic critical review on mechanisms, performance, and environmental applications.

Water pollution caused by organic and inorganic contaminants, particularly dyes and pharmaceuticals, represents a major environmental challenge. Advanced oxidation processes based on photocatalysts have emerged as efficient and sustainable approaches for water and wastewater treatment. Copper ferrite (CuFe2O4) is considered a promising photocatalyst owing to its narrow bandgap, visible-light activity, chemical stability, and magnetic properties. Despite extensive experimental investigations, a comprehensive systematic comparison of CuFe2O4-based photocatalysts under diverse operational conditions has remained limited. In this study, a systematic review following PRISMA guidelines was conducted using studies published between January 2014 and November 2025 indexed in Scopus, PubMed, Web of Science, and ScienceDirect. From an initial pool of 397 studies, 98 articles met the inclusion criteria. Key parameters - including pollutant type, pH, catalyst dosage, initial pollutant concentration, irradiation time, light source, and degradation efficiency - were quantitatively compared to identify performance trends and operational optima. The results demonstrate that CuFe2O4-based nanocomposites, particularly heterojunction, Z-scheme, and S-scheme architectures combined with TiO2, g-C3N4, graphene, and metal oxides, achieve high degradation efficiencies (often >90 %) for a wide range of organic pollutants and selected inorganic contaminants (e.g., Cr(VI)). Enhanced charge separation and suppressed electron-hole recombination were identified as the primary factors contributing to improved photocatalytic activity. In addition, the intrinsic magnetic properties of these nanocomposites enable facile catalyst recovery and reuse. In conclusion, CuFe2O4-based nanocomposites, especially those incorporating advanced heterojunction architectures, emerge as highly efficient and magnetically recoverable photocatalytic platforms for sustainable water and wastewater treatment, with strong potential for scalable implementation and real-wastewater applications.

Catalysis↗
PubMed2025

Homogeneous Gold Catalysis: Development and Recent Advances.

Gold catalysis has witnessed remarkable advances over the past decade, with numerous insightful reviews chronicling this progress. However, a comprehensive review addressing developments in the field during the post-pandemic COVID era remains notably absent. This review aims to bridge that gap by providing an in-depth analysis of recent studies, shedding light on the unique properties of gold complexes, particularly the intriguing aurophilic interactions that distinguish gold chemistry. The review systematically explores the latest achievements in both mono- and dinuclear gold-catalyzed reactions, with a focus on their applications in diverse fields, including redox coupling, asymmetric catalysis, photo-, and electrocatalysis. A special emphasis is placed on the comparative performance of mono- and dinuclear gold catalysts, with the latter often exhibiting enhanced catalytic efficiency and selectivity in certain reactions. By integrating mechanistic insights and DFT perspectives with representative experimental studies from recent years, this review highlights the significance of gold catalysis to synthetic chemistry, identifies emerging trends and outlines future directions for the field.

Catalysis↗
PubMed2007

Direct solubilization of enzyme aggregates with enhanced activity in nonaqueous media.

A protein solubilization method has been developed to directly solubilize protein clusters into organic solvents containing small quantities of surfactant and trace amounts of water. Termed "direct solubilization," this technique was shown to solubilize three distinct proteins - subtilisin Carlsberg, lipase B from Candida antarctica, and soybean peroxidase - with much greater efficiencies than extraction of the protein from aqueous solution into surfactant-containing organic solvents (referred to as extraction). More significant, however, was the dramatic increase in directly solubilized enzyme activity relative to extracted enzyme activity, particularly for subtilisin and lipase in polar organic solvents. For example, in THF the initial rate towards bergenin transesterification was ca. 70 times higher for directly solubilized subtilisin than for the extracted enzyme. Furthermore, unlike their extracted counterparts, the directly solubilized enzymes yielded high product conversions across a spectrum of non-polar and polar solvents. Structural characterization of the solubilized enzymes via light scattering and atomic force microscopy revealed soluble proteins consisting of active enzyme aggregates containing approximately 60 and 100 protein molecules, respectively, for subtilisin and lipase. Formation of such clusters appears to provide a microenvironment conducive to catalysis and, in polar organic solvents at least, may protect the enzyme from solvent-induced inactivation.

Catalysis↗