Purification and characterization of an extracellular protease from Flavobacterium arborescen

Purification and Characterization of a Metalloprotease fromChryseobacterium indologenesIx9a and Determination of the Amino Acid Specificity with Electrospray Mass Spectrometry

“…Activity decreased rapidly at temperatures above the optimal temperature. This value is slightly higher than the optimal temperatures of other proteases from psychrotrophs, which mostly had optimal temperatures of 40 -45°C (7), although optimal temperatures up to 60°C have also been recorded (15,18). …”

“…In practice this means that the naturally occurring minerals in milk might add to the thermostability of the proteases. It seems that it is specifically the Ca 2ϩ that is responsible for this heat stability of these enzymes (2,8,15,17,18,36,37). At higher temperatures, the enzyme was much more vulnerable.…”

“…The relative molecular mass of the protease from C. indologenes is lower than most of the other psychrotrophic proteases which are mostly between 40,000 and 50,000. However, relative molecular masses of between 13,000 and 28,900 have been recorded for proteases of other psychrotrophic organisms (6,15,18,34,35).…”

“…Protease activity was calculated in U ⅐ ml Ϫ1 (mol tyrosine released ⅐ min Ϫ1 ⅐ ml Ϫ1 ). The extinction coefficient of tyrosine was taken as 1380 at 280 nm (18). One unit (U) of protease activity is defined as the amount of enzyme that releases 1 mol of tyrosine per minute.…”

“…Proteolysis by these enzymes leads to the formation of short peptides, which cause off flavors and volume reductions in cheese, yoghurt, and other dairy products. Much work has already been carried out on the proteases from Pseudomonas species (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13) and to a lesser extent on the proteases from other psychrotrophic organisms such as Aeromonas (14), Micrococcus (15), Serratia (16), Bacillus (17), and Flavobacterium (18,19) species. No purification data are yet available for the extracellular proteases from Chryseobacterium species.…”