Editing of misaligned 3′-termini by an intrinsic 3′–5′ exonuclease activity residing in the PHP domain of a family X DNA polymerase

Bacillus subtilis gene yshC encodes a family X DNA polymerase (PolXBs), whose biochemical features suggest that it plays a role during DNA repair processes. Here, we show that, in addition to the polymerization activity, PolXBs possesses an intrinsic 3′–5′ exonuclease activity specialized in resecting unannealed 3′-termini in a gapped DNA substrate. Biochemical analysis of a PolXBs deletion mutant lacking the C-terminal polymerase histidinol phosphatase (PHP) domain, present in most of the bacterial/archaeal PolXs, as well as of this separately expressed protein region, allow us to state that the 3′–5′ exonuclease activity of PolXBs resides in its PHP domain. Furthermore, site-directed mutagenesis of PolXBs His339 and His341 residues, evolutionary conserved in the PHP superfamily members, demonstrated that the predicted metal binding site is directly involved in catalysis of the exonucleolytic reaction. The implications of the unannealed 3′-termini resection by the 3′–5′ exonuclease activity of PolXBs in the DNA repair context are discussed

كروماتوجرافيا السائل ذات الأداء العالي والطيف الكتلي لاسترات الليوتين من نبات التاجيتس باتيولا لين

Investigation of the xanthophyll esters of Tagetes patula L. flowers resulted in the isolation and identification of lutein, lutein dimyristate, lutein myristate palmitate, lutein dipalmitate and lutein palmitate stearate. In addition the preparation of natural yellow colour additive has been described.اسفرت دراسة المحتوى الكاروتينيدي لنبات القطيفة عن فصل وتعريف كل من زانثوفيلات الليوتين الحر وثنائي ميريسينات الليوتين وميريسيتات بالميتات الليوتين وثنائي بالميتات اليوتين وبالميتات استيارات الليوتين كما تم التعرف عليها بواسطة الطيف الكتلي لكل منها ، بالإضافة إلىِ تحضير لون أصفر طبيعي يستخدم كمكسب لون في الصناعات الغذائية والدوائية