Chitosanase: chitosan (chitosan) are widespread in nature chitinase (chitin) After deacetylation obtained, the chemical name for poly-glucosamine (1-4) -2 - amino-BD glucose, since the In 1859, the French Rouget first chitosan, the excellent performance of this natural biological functionality and compatibility, blood compatibility, security, microbial degradation of the polymer by all walks of life widespread concern in the pharmaceutical , food, chemicals, cosmetics, water treatment, metal extraction and recovery, biochemical and biomedical engineering and many other fields of applied research has made significant progress. For patients, the chitosan fat, lowering blood sugar have a research report. The brief overview chitosan chitin by deacetylation reaction product desacetyl degree (DD) determines how much of the content of amine groups (NH2) on the macromolecular chains, and DD increases, leaving the shell due to protonated amine glycans charged groups in the dilute acid solution was increased, the polyelectrolyte charge density increases, and its results will inevitably lead to changes in its structure, properties and performance, since the study of chitosan in a dilute solution properties are ignored DD values ??for the equation affected. Person VANDUM has different ionic strength on the molecular size and viscosity of chitosan in dilute solution. Concluded that the type of ionic strength will change thereby changing the degree of expansion of the random coil to the molecular size and the intrinsic viscosity results show that different DD chitosan Determination of the Mark-Houwink equation constants K, A value with changes in the value of DD. Thus by the Mark-Houwink equation constants K, A regularly dependent on the degree of deacetylation of chitosan varies, and the same molecular weight, with the increase of the degree of deacetylation of chitosan in a dilute solution of molecular size, intrinsic viscosity increase and expansion factor, while the characteristic ratio and the steric hindrance factor decrease with the increase of the degree of deacetylation. Thus any within the scope of a chitosan sample through a relatively simple intrinsic viscosity measurements, you can calculate the average molecular weight, which can accumulate some basic data for further research due to chitosan and chitin high chemical reactivity and ease of modification by chemical reagents, more research in this area, but also achieved encouraging results. Thus, through a variety of methods of chitosan modified nature. Abroad by the frozen sodium hydroxide - sodium dodecyl sulfate simple steps to prepare successful alkyl-chitin fiber alkylation to produce a variety of different chain lengths alkyl halogen compound and body volume degree, increased affinity for water or formic acid, such increased affinity is generated due to the destruction of part of the molecular crystal structure. NMR studies have shown that the hydroxyl group on C6 position Priority at the C3 position is substituted. Also prepared alkyl-chitin fibers and films. Improved nature of this affinity, there is a good value for subsequent applications of chitosan. Also preparing porous chitosan beads, heavy metals chelating , can also be used for the immobilization of biological material. Prepared by halide iodide copolymers of chitosan transplantation. Halogenated iodide method chitosan functional groups transformation iodide under mild conditions, and can produce a variety of reaction precursor. The reaction is apt to occur in the C6-bit value, for the preparation of cationic transplantation copolymer. The reaction conditions are carried out at room temperature and UV 308NM. The transformation also includes the preparation of a variety of functional groups on chitosan hydroxy chitosan.