Beta 1, 4-galactosyltransferase (β1, 4-GalTase) has been one of the most extensively studied of the glycosyltransferases. The gene has been cloned from several different species and the regulatory elements partially characterized. Controversy has surrounded the two different forms, long and short β1, 4-GalTase, as to whether or not they are equally well retained in the trans-Golgi. Putative roles of cell surface β1, 4-GalTase in cell-cell recognition and signalling have also been hotly debated. Post-translational regulation may involve features such as oligomerization of β1, 4-GalTase both with itself and with other molecules, and phosphorylation.
Fucosylation has been shown to have important functions in cell-cell interaction and cell migration in connection with physiological and pathological processes such as fertilization, embryogenesis, lymphocyte trafficking, immune responses and cancer metastasis. The human genome encodes at least five different α1, 3-fucosyltransferases. Several other enzymes transfering fucose in α1, 3-linkage, or the structures resulting from them, have been found in nearly all types of organism such as other mammals, insects, molluscs, plants and some bacteria. They differ in their substrate specificity, tissue distribution and various biochemical parameters. A short overview about these enzymes, their occurrence and probable function is given here.
In this review, the following items will be generally stated: what is a biofilm formed by bacteria, how is the biofilm concerned in our environmental conditions, and what kinds of materials do form bacterial biofilms. Formation of bacterial biofilm is originally one of the ways of constructing bacterial colonies. Bacterial biofilm consists of sticky polysaccharides excreted by bacteria and bacterial cells. Many bacterial biofilms that exist in nature have no connection with human beings. However, sometimes, bacterial biofilms are formed in or on the surfaces of structures constructed by humans, and then result in functional disorders of these structures. Biofilms that are formed in the human body by infected bacteria cause delays of the cure of diseases, because bacterial biofilms act as a protection for the bacteria from antibiotics and deffence mechanisms. The most important bacteria that cause biofilm infections in human are Pseudomonas aeruginosa and Staphylococcus epidermidis. P. aeruginosa often cause serious and chronic air tract and urinary tract infections by forming biofilms. S. epidermidis causes foreign body infections by forming biofilms on the surfaces of catheters and cannulas which are sometimes inserted into the human body to treat various diseases. The exopolysaccharide produced by P. aeruginosa is alginic acid has been well investigated. The exopolysaccharide produced by S. epidermidis is not well investigated yet. Some ways of dealing with biofilm infections are also discussed.
The hyaluronidases are a family of enzymes that have, until recently, defied thorough explication. The substrate for these enzymes, hyaluronan, is becoming increasingly important, recognized now as a major participant in such basic processes as cell motility, wound healing, embryogenesis, and implicated in cancer progression. And in those lower life forms that torment human beings, hyaluronidase is associated with mechanisms of entry and spread, e.g. as a virulence factor for bacteria, for tissue dissection in gas gangrene, as a means of treponema spread in syphilis, and for penetration of skin and gut by nematode parasites. Hyaluronidase also comprises a component of the venom of a wide variety of organisms, including bees, wasps, hornets, spiders, scorpions, fish, snakes and lizards. Of particular interest is the homology between some of these venom hyaluronidases and the enzyme found in the plasma membrane of mammalian spermatozoa, attesting to the ancient nature of the conserved sequence, a 36% identity in a 300 amino acid stretch of the enzyme protein. Clearly, hyaluronidase is of biological interest, being involved in the pathophysiology of so many important human disorders. Greater effort should be made in studying this family of enzymes that have, until recently, been overlooked.