PEROXIDASES have numerous important applications in industries and biodegradation of organopollutants , so there is a need to explore more and more sources of enzymes with different characteristics. In the present study, lignin peroxidases (LiPs) producing by fungus Humicola grisea were extracted and purified using gel filtration and ion exchange chromatography. Protein and heme protein were eluted in different peaks about 6 of these peaks had LiP activity and this is an indication that LiP in H. grisea was isoenzymes. Four of these isoenzymes were characterized regarding their molecular mass, optimum temperature and optimum pH for activity, substrate concentration and effect of some metal ions. The four purified isoenzymes have maximum activities at different temperatures, where optimum temperature for H2 and H4 isoenzyme were at 60 ºC, and the optimum temperatures for H1 and H3 were at 40 ºC and 30 ºC, respectively. The maximum activities of the four isoenzymes were within the acidic range. The different LiP isoenzymes showed different Km and Vmax values representing the varied affinity of the four isoenzymes using veratryl alcohol as a substrate. Km values for H1, H2, H3 and H4 were 5.26, 5.0, 1.3 and 1.4, respectively. While Vmax values for the same isoenzymes were 1.25, 0.8, 0.87 and 1.1, respectively.

H an y A . M oub as h er F at m a A . m os t af a O m i m a har ou n Optimiz ation of p eroxidas e productio n of Humicol a gri sea T raaen and its applic ation in biod egradatio n of textile dy es ABSTRACT:Per oxidases are import ant group of enz ym es that play a m ajor rol e in biodegrad ation of organo-pollut ants. Eight f ungal isol at es wer e isolat ed, id enti fied, and t est ed for t heir peroxidas e producti on and de-c olorization activit y. S unzol Brilliant Or ange and S uncron Blue days wer e chos en for t his inv estigati on. All fu ngal is olat es gave p ositive ability; how ev er, the highes t percent age of decolorization w as obtai ned using H umicol a grisea. Lignin per oxidas es of Humic ola gris e the m ost p otent f ung us, w as st udied regarding optimal c ultur e c onditions of prod uction. The highes t produc tion of ligni n per oxidas es (LiPs) was obt ained usi ng Kirk and Tien medium s upplemented with 10 g l -1 sucr os e as a c arbon s ource and 0. 5 g l -1 amm oni um hydrogen phosp hate as a nitrogen source. The optimum t emperat ure f or Li Ps produc tion was at 30°C, w hile the optimum pH w as at 4. KEY WORDS:Per oxidase, H umicola gris ea Traaen, textile dyes, biodegrad ation, organo-pollutants . CORRESP ONDENCE:H an y A . M oub as h er ) . S ynthetic d yes ar e us ed i n t extil e d yei ng , p ap er pri nti ng , l eat her dyei ng , phar mac e uti c als , c ol or p hot ogr ap hy, cosm eti cs , pl ast ic , f ood addi tiv e, p etr ol eum prod uc ts and m any i nd us tri al pr oduct s (A ndl eeb et al. , 2010) .