Question

acid amino in four changes in the eberal point mutations, resulting e encoded proteins. These changes are listed below: Position in iAlde Amino Acid Gly Met Amino Acid 176 235 266 268 Gly Leu Gly Ala The DNA sequence of the coding strand in the region which encodes amino adds 266 and 268 of the I and I alleles is shown below (differences shown in type): Sequence of I allele: Sequence of I allele: .ACTACATGGGGGCGTTCTT.. e) Based on the mutation data, indicate the reading frame of the DNA sequences above. differ at four places, only two of these contribute to their substrate specificity (the other two contribute only slightly to the substrate specificity). The structures of the active sites of the A and B forms of the blood type glycosyltransferase are shown below with their respective sugar substrates UDP-Gal UDP-GalNAc UDP CH3 HO он сн, 268 266 "A form" enzyme 266 B form" enzyme Based on these figures, explain how the different forms of the glycosyltransferase have different substrate specificities.

Answer 1

266 Leu 26 2 wence baseahesion Hat coles amino aoid a 266, 268sim of each allal, is %iven 268 266

According da the -genti e cedo, leo→ CTT, CTC,CTA, CTG 1 GCC Gcq we jot need to id Ihem ivo the open med atrove acuoroling

f) The A form enzyme has 2 methyl branches in its 266 position and a H atom at its 268 position . So at 266 position it can for H bond between the substrate Oxygen and H of methyl. At 268 position it can again form H bond between the H present at 268 position and the O of OH group of the substrate just like earlier.

The B form of enzyme has a methyl branch at both 266 and 268 position .so it can form only H bond with substrate having a O or N in it .