Table II.

Comparison of Calculated Latent Amino Acid Side-Chain Coefficients and RP-HPLC-Derived Amino Acid Coefficients

Amino Acid	Latenta Coeffs.	Group 1b (-GX-OH)				Group 2 (-GX-amide)				Group 3 (Ac-XG-)				Group 4 (NH3+-XG-)				Group 5 (-GXG-)
		Coeffs.c	Normd	Norm ’e	Δ f	Coeffs.	Norm	Norm ’	Δ	Coeffs.	Norm	Norm ’	Δ	Coeffs.	Norm	Norm ’	Δ	Coeffs.	Norm	Norm ’	Δ
Trp	100.00	40.0	100.00	94.49	−5.51	36.5	100.00	100.98	0.98	33.2	100.00	100.77	0.77	27.9	100.00	114.50	14.50	22.9	100.00	101.14	1.14
Phe	90.17	37.0	92.98	87.71	−2.46	32.9	90.24	91.30	1.13	29.6	89.42	90.17	0.00	22.3	80.13	92.23	2.06	20.6	91.00	91.61	1.44
Leu	73.84	32.2	81.75	76.84	3.00	26.0	71.52	72.74	−1.10	23.7	72.09	72.80	−1.04	15.8	57.07	66.37	−7.47	16.8	76.13	75.86	2.02
Ile	69.53	30.5	77.77	73.00	3.47	25.2	69.35	70.59	1.06	21.8	66.51	67.20	−2.33	14.2	51.39	60.01	−9.52	15.3	70.26	69.65	0.12
Met	51.64	21.2	56.00	51.95	0.31	18.0	49.82	51.22	−0.42	16.5	50.94	51.60	−0.04	11.8	42.87	50.46	−1.18	11.2	54.22	52.66	1.02
Tyr	47.49	18.9	50.62	46.74	−0.75	16.4	45.48	46.92	−0.57	15.6	48.30	48.95	1.46	12.8	46.42	54.44	6.95	8.2	42.48	40.23	−7.26
Val	44.60	20.0	53.19	49.23	4.63	15.4	42.77	44.23	−0.37	13.8	43.01	43.65	−0.95	8.1	29.74	35.74	−8.86	8.6	44.04	41.89	−2.71
Pro	27.54	12.2	34.94	31.58	4.04	7.5	21.34	22.97	−4.57	10.2	32.43	33.05	5.51	4.5	16.97	21.42	−6.12	3.6	24.48	21.17	−6.37
Cys	26.84	10.8	31.66	28.41	1.57	8.6	24.33	25.93	−0.91	8.1	26.26	26.87	0.03	4.3	16.26	20.63	−6.21	6.0	33.87	31.12	4.28
Ala	13.26	5.0	18.09	15.29	2.03	3.0	9.14	10.87	−2.39	3.4	12.46	13.03	−0.23	1.5	6.32	9.49	−3.77	2.8	21.35	17.86	4.60
Glu	11.12	2.1	11.30	8.73	−2.39	3.8	11.31	13.02	1.90	3.1	11.58	12.15	1.03	1.4	5.97	9.09	−2.03	2.3	19.39	15.79	4.67
Thr	11.64	3.6	14.81	12.12	0.48	3.3	9.95	11.68	0.04	2.8	10.69	11.26	−0.38	1.9	7.74	11.08	−0.56	1.5	16.26	12.47	0.83
Arg	10.24	2.5	12.23	9.63	−0.61	3.7	11.04	12.75	2.51	2.4	9.52	10.09	−0.15	3.0	11.65	15.46	5.22	−1.1	6.09	1.70	−8.54
Asp	8.15	1.4	9.66	7.14	−1.01	1.9	6.15	7.91	−0.24	1.7	7.46	8.03	−0.12	1.4	5.97	9.09	0.94	1.5	16.26	12.47	4.32
Gln	6.00	0.0	6.38	3.97	−2.03	1.6	5.34	7.10	1.10	0.7	4.53	5.08	−0.92	1.4	5.97	9.09	3.09	0.8	13.52	9.57	3.57
Gly	3.80	0.0	6.38	3.97	0.17	0.0	1.00	2.80	−1.00	0.0	2.47	3.02	−0.78	0.0	1.00	3.52	−0.28	0.0	10.39	6.26	2.46
His	4.14	0.0	6.38	3.97	−0.17	1.2	4.25	6.03	1.89	0.0	2.47	3.02	−1.12	1.4	5.97	9.09	4.95	−2.4	1.00	−3.68	−7.82
Ser	3.53	−0.8	4.51	2.16	−1.37	0.0	1.00	2.80	−0.73	0.0	2.47	3.02	−0.51	0.0	1.00	3.52	−0.01	0.6	12.74	8.74	5.21
Lys	2.92	−1.0	4.04	1.71	−1.21	0.0	1.00	2.80	−0.12	−0.3	1.59	2.14	−0.78	1.3	5.61	8.69	5.77	−2.3	1.39	−3.27	−6.19
Asn	1.00	−2.3	1.00	−1.23	−2.23	0.0	1.00	2.80	1.80	−0.5	1.00	1.55	0.55	0.0	1.00	3.52	2.52	−0.5	8.43	4.19	3.19
					Aveg				Ave.				Ave.				Ave.				Ave.
					1.97				1.24				0.94				4.60				3.89

^aCalculated coefficients derived from the five peptide groups shown in Table I by latent regression modeling (see Computational Methods for details).

^bThe sequences of peptide Groups 1-5 are shown in Table I.

^cPeptide mixtures were eluted from a Kromasil C₁₈ column (150 × 2.1 mm I.D., 5 μm particle size, 100 Å pore size) by a linear AB gradient (0.25% B/min) at a flow-rate of 0.3 ml/min and a temperature of 25°C, where eluent A was 20 mM aq. TFA containing 2% (v/v) acetonitrile and eluent B was 20 mM TFA in acetonitrile; coefficients were subsequently expressed as peptide retention time relative to the Gly-substituted peptide for that sequence.

^dCoefficient normalization was achieved by assigning a value of 100 and 1, respectively, to the highest and lowest RP-HPLC derived coefficients, thus being consistent with the approach to calculation of the latent coefficients.

^eNorm ’ denotes adjustment of the normalized coefficients of all five peptide groups to achieve a slope of 1.0 and an intercept of zero when plotted against the calculated latent coefficients (Figure 2C).

^fΔ denotes deviation of RP-HPLC-derived coefficients (Norm ’ values) and calculated latent coefficients.

^gAverage of absolute Δ values.