Cloning, expression, purification, and characterization of novel l-glutamin-(asparagin-)‎ase from klebsiella pneumoniae MGH78578

العناوين الأخرى

استنسال، تعبير، تنقية و توصيف L-glutamin-(asparagin-)‎ase الجديد و المعزول من Klebsiella pneumoniae MGH 78578

مقدم أطروحة جامعية

al-Bahrani, Maha Hamid Abd Allah

مشرف أطروحة جامعية

Aziz, Ghazi Munim
al-Qazzaz, Abd al-Karim Abd al-Razzaq Abd al-Wahhab

الجامعة

جامعة بغداد

الكلية

كلية العلوم

القسم الأكاديمي

قسم التقانة الإحيائية

دولة الجامعة

العراق

الدرجة العلمية

دكتوراه

تاريخ الدرجة العلمية

2014

الملخص الإنجليزي

This study is one among a few of studies that have been reported on the bacterial L-glutamin-(asparagin-)ase.

In this study, a pair of primers were designed to obtain L- glutamin-(asparagin-)ase encoding gene from Klebsiella pneumoniae subsp.

pneumoniae MGH 78578.

The Enzyme encoding gene (KPN-01165) was cloned into an N-term 6X HN(pLEICS-01) vector.

The recombinant vector was then transformed into E.coli DH5α to be later checked for the correct orientation of the insertion gene by PCR technique using the primers.

The latter was designed previously to obtain enzyme encoding gene (KPN-01165).

Results of agarose gel electrophoresis have shown that KPN-01165 was inserted into the correct orientation in only few clones.

L- glutamin-(asparagin-)ase encoding gene (KPN-01165) was sequenced and compared with the gene sequenced of NCBI.

Compression results revealed that the homogeneity of KPN-01165 sequence was 100%.

Agarose gel electrophoresis revealed that the molecular weight of L- glutamin-(asparagin)ase gene was 1005 bps, which encodes a protein of 334 amino acids.

Escherichia coli BL21(DE3) plysS-T1R was used to express and produce the recombinant enzyme.

The recombinant enzyme containing a 6xHistidin-tag can be easily purified by Ni-NTA chromatography.

Besides, its molecular weight was determined to be 40 KDa by SDS-PAGE.

Sequencing the purified L-glutamin-(asparagin-)ase was done by matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

The biochemical properties of a novel recombinant L-glutamin-(asparagin-)ase were studied in the presence of L-glutamine(L-Gln) and L- asparagine (L-Asn) as 00 substrates.

The highest activity of the enzyme has been shown at pH 8.

It has also been noticed the maximum activity of L-glutamin-(asparagin-)ase was o.994 and 1.006 IU/ml towards L-asparagine and L-glutamine, respectively.

Whereas the optimum pH for enzyme stability was found to be at pH 7 and 8.

On the other hand, enzyme activity at 37 and 40 °C.

Moreover, the enzyme kept more than 90% of its activity at temperature degrees ranged between 25-37 °C for 30 min.

The enzymatic L-glutamin-(asparagin-)ase activities increased in the presence of 5% of NaCl in the reaction buffer.

Metal ions, such as MgSO4.7H2O, CuSO4.5H2O, FeSO4.7H2O, CaCl2 2H2O and KCl have a slight effect on the activity of the enzyme at a concentration of 5mM.

Accordingly, both enzymatic activities were not modified in the presence of EDTA at 2 and 5 mM while the remaining enzyme activity % was reduced into 74% and 68% in the presence of each 5mM of 2-mercaptoethanol (2-ME) and DTT, respectively.

Finally, the results of enzyme Kinetics have showed that the Km and Vmax values of L-glutamin-(asparagin-)ase were 0.067 mM and 0.042 mM /min towards L-asparagine and 0.054 mM and 0.041 mM/min towards L-glutamine, respectively.

The expression of L-glutamin-(asparagin-)ase (KPN_01165) and glutaminase (KPN_01636) genes were induced in the presence of 2mM of asparagine, glutamine, or asparagine and glutamine relative to valine.

The results have showed that the expression of both KPN_01165 and KPN_01636 genes increased significantly when K.

pneumoniae was grown in a medium supplemented with either of these amino acids singly or in a combination relative to valine.

Many tests were done to determine the distribution of L-glutamin-(asparagin-)ase from K.

pneumoniae subsp.

pneumoniae MGH 78578.

Results show that the 04 highest enzyme activities were seen in whole cell extract in comparison with the periplasmic extract and supernatant

التخصصات الرئيسية

الأحياء

الموضوعات

• الأحماض الأمينية

عدد الصفحات

178

قائمة المحتويات

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-601456