10.12.2012 Views

netLibrary - eBook Summary Structure-based Drug Design by ...

netLibrary - eBook Summary Structure-based Drug Design by ...

netLibrary - eBook Summary Structure-based Drug Design by ...

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

Document<br />

Figure 7<br />

Cartoon representation of the HIV PR dimer. The sites of primary<br />

resistance-causing mutations in the active site are indicated. For clarity, the names of the<br />

residues are shown for one monomer only.<br />

Page 29<br />

mutations (ten assuming the dimeric nature of HIV PR) changed the susceptibility of the resistant strain<br />

to indinavir <strong>by</strong> only eight-fold if compared to the wild type HIV.<br />

The resistance-causing mutations are localized in a few “hot spots” in the structure of HIV PR and can<br />

be divided into two groups. The first group consists of the primary mutations located directly in the<br />

active site and includes changes at residues Val82/82', Ile84/84', somewhat less frequently at Gly48/48'<br />

and, in the case of nelfinavir, Asp30/30' (Figure 7). Residues 82/82' and 84/84' are located on the<br />

flexible loops that form the outer walls of the S3/S3' and S1/S1' subsites, respectively. In the resistant<br />

variants, valine 82/82' is most frequently substituted <strong>by</strong> the smaller side chain of alanine or the larger<br />

side chains of phenylalanine or isoleucine [57,58]. The change in position 82/82' is usually accompanied<br />

<strong>by</strong> a substitution of Ile84/84', most commonly to the smaller amino acids alanine or valine [57]. From<br />

the clinically tested compounds, ritonavir and indinavir, which were optimized to form strong<br />

hydrophobic interactions with the side chain of Val82/82' in the S3 subsite, suffer most significantly<br />

from any change at this position. On the other hand, the antiviral activities of saquinavir, and nelfinavir,<br />

which do not form any interaction in the S3/S3' subsite are not affected <strong>by</strong> mutations at Val82/82' and<br />

are only marginally cross resistant to changes involving Ile84/84' [57,58,62]. The resistance-causing<br />

http://legacy.netlibrary.com/nlreader/nlReader.dll?bookid=12640&filename=Page_29.html [4/5/2004 4:46:39 PM]

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!