Identification and characterization of hydrolytic enzymes of sunn pest (eurygaster integriceps) and cotton bollworm (helicoverpa armigera)

Özgür, Ebru
In this study, hydrolytic enzymes from sunn pest (Eurygaster integriceps) and cotton bollworm (Helicoverpa armigera) midguts were identified and characterized in terms of their optimum pH, Km and Vmax values. Hydrolytic activities were also tested for inhibition by several protease and alpha-amylase inhibitors which can be used for the development of insect resistant plants through transgenic technologies. For sunn pest midgut, a low proteolytic activity, belonging mostly to trypsin-like and leucine aminopeptidase-like proteases, and a very high alpha-amylase activity was found in sunn pest midgut, reflecting its high carbohydrate diet. Proteolytic activities could not be inhibited by natural protease inhibitors (SBTI and aprotinin) but inhibited significantly by a general serine protease inhibitor PMSF and metalloprotease inhibitors CdCl2 and CuCl2. alpha-Amylase activity of sunn pest midgut is resistant to inhibition by bean alpha-amylase inhibitor, but inhibited by chickpea, wheat and maize alpha-amylase inhibitors by 26 %, 37 % and 40 %, respectively. For cotton bollworm midgut, a very high proteolytic activity, belonging to serine and metalloprotease type, was detected. alpha-Amylase activity was lower compared to sunn pest midgut, but there were higher and diverse type of proteases, might be reflecting its wide range of host preference. Proteolytic activity was significantly inhibited by both natural protease inhibitors (SBTI and aprotinin). It was also inhibited by several synthetic protease inhibitors (PMSF, E-64, TPCK, CdCl2, CuCl2, Chymostatin). alpha-Amylase activity was inhibited by 60 % by wheat alpha-amylase inhibitor, while maize, chickpea and bean alpha-amylase inhibitors had no effect on cotton bollworm midgut alpha-amylase activity.


Identification and characterization of hydrolytic enzymes from the midgut of Sunn Pest of wheat (Eurygaster integriceps)
Ogur, E.; YÜCEL, MUSTAFA; Öktem, Hüseyin Avni (Informa UK Limited, 2009-01-01)
To help in the development of Sunn Pest-resistant transgenic plants employing protease or alpha-amylase inhibitors, midgut hydrolytic enzymes of Sunn Pest (Eurygaster integriceps, Put.) (Heteroptera: Scutelleridae) were identified and characterized biochemically. We observed levels of very low proteolytic activity of trypsin (3 nmoles/min/mg), elastase (0.66 nmoles/min/mg) and leucine aminopeptidase-like (14.4 nmoles/min/mg) proteases, but no chymotrypsin and papain-like activity. Proteolytic activities wer...
Identification and characterization of hydrolytic enzymes from the midgut of the cotton bollworm, Helicoverpa armigera Hubner (Lepidoptera: Noctuidae)
Ozgur, Ebru; Yucel, Meral; Öktem, Hüseyin Avni (2009-01-01)
Midgut hydrolytic enzymes of Helicoverpa armigera Hubner (Lepidoptera: Noctuidae) were identified and partially characterized. K-m, V-max, optimum pH, and specific activity were determined for proteolytic enzymes and alpha-amylases. All hydrolytic enzyme activity had an optimum pH value in the alkaline pH range. We observed major serine protease activity, together with minor cysteine-like activity, the former being significantly inhibited by soybean trypsin inhibitor (SBTI) and aprotinin. Moreover, differen...
MELLATI, AA; YUCEL, M; ALTINORS, N; Gündüz, Ufuk (1993-10-01)
The M2-type pyruvate kinase was purified from human meningioma by ammonium sulfate precipitation, followed by ion exchange and affinity chromatography. The specific activity of the purified enzyme was 33.4 U/mg with a yield of 6.5%.
Characterization of bacteriocins from two Lactococcus lactis subsp lactis isolates
Akcelik, O; Tukel, C; Özcengiz, Gülay; Akcelik, M (Wiley, 2006-03-01)
In this study, bacteriocins from two Lactococcus lactis subsp. lactis isolates from raw milk samples in Turkey designated OC1 and OC2, respectively, were characterized and identified. The activity spectra of the bacteriocins were determined by using different indicator bacteria including Listeria, Bacillus and Staphylococcus spp. Bacteriocins were tested for their sensitivity to different enzymes, heat treatments and pH values. Loss of bacteriocin activities after alpha-amylase treatment suggested that they...
Characterization of extracellular beta-lactamases from penicillin G-resistant cells of Streptococcus thermophilus
Chirica, LC; Güray, Nülüfer Tülün; Gültekin, Güzin Candan; Bozoglu, F (International Association for Food Protection, 1998-07-01)
In this study, biochemical properties of two extracellular beta-lactamases produced by penicillin-resistant Streptococcus thermophilus cells were investigated. Both beta-lactamases showed specificity for penicillins but not for cephaloridins. The p-lactamases exhibited different affinities for penicillin G. The one with the higher molecular weight (F1) had a K(m) value of 3.44 mu M and a V(max), value of 8.33, mu mol/min/mg of protein, whereas the beta-lactamase with the lower molecular weight (FII) had a K...
Citation Formats
E. Özgür, “Identification and characterization of hydrolytic enzymes of sunn pest (eurygaster integriceps) and cotton bollworm (helicoverpa armigera),” Ph.D. - Doctoral Program, Middle East Technical University, 2006.