TABLE 3.

HIV-1 and FIV PR cleavage of FIV PR selected phage-derived peptides^a

Peptide	Peptide sequencec	HIV-1 PR cleavageb	FIV PR cleavageb
R3 20	KGSGVF↓AVTQLVPK	++	+++
R2 13	KGSGIY↓TVQSLVPK	++	+++
R1 8	KGSGLTM↓VTQLVPK	−	+++
R3 21	KGSGVY↓QL d SALVPK	+	++, ++d
R2 20	KGSGALTN↓AVLVPK	−	+++
R3 14	KGSGAMVN↓QALVPK	−	+++
R3 25	KGSGTW↓MVHSLVPK	−	+++
R3 30	KGSGGRIN↓VALVPK	+	+++

^aAll peptide sequences listed above were derived from phage selected as described in Materials and Methods. A 500 μM concentration of each peptide was digested with 312 nM FIV PR or 160 nM HIV-1 PR for 2 h at pH 6.7 in 0.2 M NaCl. 

^b−, peptide cleavage not detected by HPLC; +, peptide cleavage detected at <5%; ++, peptide cleavage detected at between 10 and 90%; +++, 100% cleavage of the peptide. 

^cCleavage site for both HIV-1 PR and FIV PR is denoted by an arrow as determined by mass spectrometry of the cleaved fragments. 

^dFIV PR cleaved peptide R3 21 at two sites, the second marked by this footnote reference. None of the starting peptide remained after cleavage, and each product was identified at >20% of the original peptide concentration.