Aspartic proteinases in Antarctic fish

Sulfonamide inhibition studies of the γ-carbonic anhydrase from the Antarctic bacterium Pseudoalteromonas haloplanktis

“…4-11 These enzymes are characterized by a specific activity at low and moderate temperatures higher than their mesophilic counterparts over a temperature range roughly covering 0-30°C and by a relative instability. 6,7,[11][12][13] Probably, in the case of psychrophilic microorganisms the selective pressure is essentially exerted towards the specific activity and not towards stability factors as happens in mesophilic or in thermophilic enzymes. The molecular structure of a 'cold-enzyme' is primarily characterized by an adequate plasticity of the molecule at the environmental temperature in order to accommodate the substrates with a minimum of energy expenditure.…”

“…3 Cold-adapted organisms have developed a number of adjustments at the molecular level to maintain metabolic functions at low temperatures, such as the production of enzymes, note as 'cold-enzyme'. [4][5][6][7][8][9][10][11] These enzymes are characterized by a specific activity at low and moderate temperatures higher than their mesophilic counterparts over a temperature range roughly covering 0-30°C and by a relative instability. 6,7,[11][12][13] Probably, in the case of psychrophilic microorganisms the selective pressure is essentially exerted towards the specific activity and not towards stability factors as happens in mesophilic or in thermophilic enzymes.…”

“…There is a continuum in the adaptation of a protein to its environment. [4][5][6][7][8][9][10][11]13,[15][16][17][18][19][20][21][22] In fact, all known structural factors and weak interactions involved in protein stability are either reduced in number or modified in psychrophilic enzymes in order to increase their flexibility; but the same structural factors are also implicate for increasing the stability of the thermophilic proteins. [23][24][25][26][27][28][29] Carbonic anhydrases (CAs; EC 4.2.1.1) are metalloenzymes that catalyze CO 2 hydration to bicarbonate and protons.…”

Fish pepsin: basic characteristics, extraction, determination and biotechnological applications

“…Natural Resources, Aquidabã, v.4, n.1, Set, Out, Nov, Dez 2013, Jan, Fev, Mar, Abr, Mai, Jun, Jul The zymogen is converted to the active form through conformational changes and bond cleavage, leading to the opening of the active site by the removal of the prosegment from the active center of the enzyme (RICHTER et al, 1998, SHAHIDI & KAMIL, 2001KAGEYAMA, 2002;ROTTA, 2003;KOOLMAN & ROEHM, 2005;DE LUCA et al, 2009;ZHOU et al, 2008;WU et al, 2009;ZHAO et al, 2011).…”

“…It is included in the category of endopeptidases (only operates on internal links of the chain) which cleave peptide bonds of proteins by their amino terminal side of aromatic amino acid residues, such as tyrosine and tryptophan, breaking the long polypeptide chains into smaller peptides and free amino acids in some (WHITAKER, 1994;DÍAZ-LÓPEZ et al, 1998;RICHTER et al, 1998;RAO et al, 1998;SHAHIDI & KAMIL, 2001;ROTTA, 2003;KOOLMAN & ROEHM, 2005;KLOMKLAO et al, 2007;DE LUCA et al, 2009;WU et al, 2009;ZHAO et al, 2011).…”