جستجوی مقالات مرتبط با کلیدواژه "denaturant" در نشریات گروه "زیست شناسی"

Lysozyme is a key molecule in innate immune system and plays a vital role in the immune systems of many species against bacterial species with hydrolysis of glycosidic bonds between N-acetylglucosamine and N-acetylmuramicacid of the peptidoglycan layer in the bacterial cell wall and infectional microorganisms. The highest activity of the enzyme in marine species has reported in kidney and spleen. In the present study, lysozyme was extracted from adrenal gland of Caspian Sea Rutilus frisii kutum; then, partially purified by ammonium sulfate and properties such as pH and optimum temperature as well as salt and denaturant concentrations on enzyme activity was evaluated. The enzyme activity was assayed using a suspension of Micrococcus lysodeikticus as substrate. Based on the results, the optimum pH and temperature was found 6 and 45ºC, respectively. Furthermore, lysozyme activity is dependent on salt concentration.

Amylolytic enzymes are among the most important enzymes in food, pharmaceuticals, detergent industries and biotechnology. Alpha amylases cleave the linkage between adjacent glucose units in the linear amylose chain and ultimately generate glucose, maltose and maltotriose units. Although many microorganisms such as Bacillus licheniformis, Bacillus amyloliquifaciens produce this enzyme, Aspergillus niger as most popular one is used in industrial applications. In the present study, a strain of amylolitic Anoxybacillus sp. was identified. 16SrDNA analysis was carried out and bacterial optimal growth and production was investigated. Moreover, enzyme was partially purified and biochemical properties such as temperature, optimum pH and the effect of denaturants like SDS on the stability of enzyme were evaluated. On the other hand, encoded gene of enzyme was amplified and sequenced. Results indicated that after 20 hours, the optimal conditions for bacterial growth were at 60ºC and pH of 7. Also, maximum enzyme activity was obtained at 75ºC at pH 6 after 72 h of incubation. Enzyme showed higher optimum temperature but similar stability against SDS in comparison with other similar.

Thermolysin is a thermostable protease produced by Bacillus thermoproteolyticus. This enzyme is industrially applicable especially for peptide synthesis. Due to industrial applications، numerous investigations have been performed on thermolysin. In the present study، the role of calcium on thermal، acidic pH، denaturant (urea and SDS) and salt stabilities was studied. In the absence of calcium، t1/2 at 80، 85 and 90 ÛC was 7، 3 and 1 min، respectively. However، in the presence of 10 mM calcium، t1/2 at the same temperatures was >95، 45 and 16 min، respectively. On the other hand، calcium had marginal effect on the pH stability of enzyme. The analyses revealed that SDS and urea contrarily affect on the enzyme stability. The concentration of SDS by which the enzyme activity diminished by half was 0. 1 and 0. 9 (%W/V) in the presence and absence of calcium، respectively. Oppositely، urea did not reduced and even promoted the enzyme activity in both conditions. Stability of thermolysin in NaCl up to 3M was slightly increased in the presence of calcium while slightly decreased in the absence of calcium. At higher concentrations of NaCl، however، the stability was decreased in both conditions. These results reveal that thermal and SDS stability of thermolysin are strongly Ca-dependent، stability against NaCl and urea are moderately Ca-dependent، and its acidic pH stability is Ca-independent.