G8: a novel domain associated with polycystic kidney disease and non-syndromic hearing loss.

UNLABELLED: We report a novel protein domain-G8-which contains five repeated beta-strand pairs and is present in some disease-related proteins such as PKHD1, KIAA1199, TMEM2 as well as other uncharacterized proteins. Most G8-containing proteins are predicted to be membrane-integral or secreted. The G8 domain may be involved in extracellular ligand binding and catalysis. It has been reported that mis-sense mutations in the two G8 domains of human PKHD1 protein resulted in a less stable protein and are associated with autosomal-recessive polycystic kidney disease, indicating the importance of the domain structure. G8 is also present in the N-terminus of some non-syndromic hearing loss disease-related proteins such as KIAA1109 and TMEM2. Discovery of G8 domain will be important for the research of the structure/function of related proteins and beneficial for the development of novel therapeutics. CONTACT: liangsp@hunnu.edu.cn

Recent progress on immobilization of enzymes on molecular sieves for reactions in organic solvents.

Enzymes exhibit high selectivity and reactivity under normal conditions but are sensitive to denaturation or inactivation by pH and temperature extremes, organic solvents, and detergents. To extend the use of these biocatalysts for practical applications, the technology of immobilization of enzymes on suitable supports was developed. Recently, these immobilized biomolecules have been widely used and a variety of immobilization supports have been studied. The majority of these supports cover diverse kinds of materials such as natural or synthetic polyhydroxylic matrixes, porous inorganic carriers, and all kinds of functional polymers. Microporous molecular sieve, zeolite, has attracted extensive interest in research because of its distinctive physical properties and geochemistry. Recently, with the discovery of a new family of mesoporous molecular sieves, MCM-41, this series of materials shows great potential for various applications. Molecular sieves involve such a series of materials that can discriminate between molecules, particularly on the basis of size. As support materials, they offer interesting properties, such as high surface areas, hydrophobic or hydrophilic behavior, and electrostatic interaction, as well as mechanical and chemical resistance, making them attractive for enzyme immobilization. In this article, different types of molecular sieves used in different immobilization methods including physical adsorption on zeolite, entrapment in mesoporous and macroporous MCM series, as well as chemically covalent binding to functionalized molecular sieves are reviewed. Key factors affecting the application of this biotechnology are discussed systematically, and immobilization mechanisms combined with newly developed techniques to elucidate the interactions between matrixes and enzyme molecules are also introduced.