Cu(II) and Ni(II) Interactions with the Terminally Blocked Hexapeptide Ac-Leu-Ala-His-Tyr-Asn-Lys-amide Model of Histone H2B (80–85)

Table 4

Spectroscopic parameters of Cu(II) and Ni(II) complexes of -LAHYNK-.

Species	UV/Vis	CD	EPR
	𝜆max(𝜀/M^−1cm^−1)	𝜆max(Δ𝜀/M^−1cm^−1)	A||(G)	g||
Cu(II) complexes
CuH2L (1N)	*	331 (−0.33)^(b)691 (0.11)^(a)	*
CuL (3N)	591 (110)	338 (−0.98)^(b), (c) 637 (+0.30)^(a)	170	2.230
CuH-1L (3N)	582 (94)	299 (+0.86)^(c)339 (−0.68)^(b)	173	2.231
		637 (+0.26)^(a)
CuH-2L (4N)	528 (120)	297 (1.00)^(c), 343 (−0.39)^(b)	196	2.190
		475 (−0.54)^(a) 622 (+0.39)^(a)
CuH-3L (4N)	518 (140)	300 (+1.05)^(c), 348 (−0.15)^(b)	196	2.180
		484 (−0.93)^(a)614 (0.55)^(a)
CuH-4L (4N)	515 (150)	302 (+0.58)^(c) 346 (−0.17)^(b)	196	2.180
		490 (−1.30)^(a)624 (0.66)^(a)
Ni(II) complexes
NiH2L (1N )	*	*	—
NiHL (2N)	*	329 (+0.34)^(b), (c)	—
		416 (−0.94)^(a)
NiH−1L (4N)	422 (84)	336 (+0.06)^(b), (c) 564 (+1.08)^(a)	—
		416 (−1.23)^(a)
NiH−2L (4N)	434 (140)	338 (−0.03)^(b), (c)514 (+1.36)^(a)	—
		416 (−2.23)^(a)
NiH−3L (4N)	436 (130)	336 (+0.32)^(b), (c) 514 (+0.80)^(a)	—
		416 (−3.32)^(a)

^(a)d-d transitions of metals, ^(b)CTN_im→M, ^(c)N⁻→M, where M = Cu(II) or Ni(II).^*These species could not be detected spectroscopically because of their low concentrations and/or overlap with others.