L-Me­thion­yl-L-tyrosine monohydrate

The study of the oxidation of various proteins necessitates scrutiny of the amino acid sequence. Since me­thio­nine (Met) and tyrosine (Tyr) are easily oxidized, peptides that contain these amino acids are frequently studied using a variety of oxidation methods, including, but not limited to, pulse radiolysis, electrochemical oxidation, and laser flash photolysis. To date, the oxidation of the Met–Tyr dipeptide is not fully understood. Several investigators have proposed a mechanism of intra­molecular electron transfer between the sulfide radical of Met and the Tyr residue. Our elucidation of the structure and absolute configuration of L-Met–L-Tyr monohydrate, C₁₄H₂₀N₂O₄S·H₂O (systematic name: (2S)-2-{[(2S)-2-amino-4-methyl­sulfanyl­butano­yl]amino}-3-(4-hy­droxy­phen­yl)propanoic acid monohydrate) is presented herein and provides information about the zwitterionic nature of the dipeptide. We suspect that the zwitterionic state of the dipeptide and its inter­action within the solvent medium may play a major role in the oxidation of the dipeptide. In the crystal, all the potential donor atoms inter­act via strong N—H...O, C—H...O, O—H...S, and O—H...O hydrogen bonds.

Key indicators

Structure: I

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.025
• wR factor = 0.064
• Data-to-parameter ratio = 13.6

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT220_ALERT_2_C NonSolvent   Resd 1  C   Ueq(max)/Ueq(min) Range        3.1 Ratio
PLAT987_ALERT_1_C The Flack x is >> 0 -  Do a BASF/TWIN Refinement     Please Check

Alert level G
PLAT033_ALERT_4_G Flack x Value Deviates > 3.0 * sigma from Zero .      0.031 Note
PLAT480_ALERT_4_G Long H...A H-Bond Reported H6       ..O1W      .       2.61 Ang.
PLAT480_ALERT_4_G Long H...A H-Bond Reported H11      ..O1       .       2.66 Ang.
PLAT480_ALERT_4_G Long H...A H-Bond Reported H12A     ..O2       .       2.65 Ang.
PLAT720_ALERT_4_G Number of Unusual/Non-Standard Labels ..........          1 Note
PLAT802_ALERT_4_G CIF Input Record(s) with more than 80 Characters          3 Info
PLAT910_ALERT_3_G Missing # of FCF Reflection(s) Below Theta(Min).          1 Note
PLAT912_ALERT_4_G Missing # of FCF Reflections Above STh/L=  0.600         13 Note
PLAT978_ALERT_2_G Number C-C Bonds with Positive Residual Density.          8 Info

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   2 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   9 ALERT level G = General information/check it is not something unexpected

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   7 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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Computing details

Data collection: APEX2 (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: Mercury (Macrae et al., 2020) and ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: publCIF (Westrip, 2010).

L-Methionyl-L-tyrosine monohydrate

Crystal data

C14H20N2O4S·H2O	Dx = 1.360 Mg m^−3
Mr = 330.39	Cu Kα radiation, λ = 1.54184 Å
Orthorhombic, P212121	Cell parameters from 7969 reflections
a = 5.4826 (3) Å	θ = 3.8–69.4°
b = 12.4971 (7) Å	µ = 2.01 mm^−1
c = 23.5451 (13) Å	T = 100 K
V = 1613.23 (15) Å^3	Lath, colourless
Z = 4	0.29 × 0.08 × 0.02 mm
F(000) = 704

Data collection

Bruker Kappa APEXII DUO CCD diffractometer	3002 independent reflections
Radiation source: IµS microfocus	2854 reflections with I > 2σ(I)
QUAZAR multilayer optics monochromator	Rint = 0.040
φ and ω scans	θmax = 69.4°, θmin = 4.0°
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	h = −4→6
Tmin = 0.777, Tmax = 0.961	k = −14→15
14990 measured reflections	l = −28→28

Refinement

Refinement on F^2	Hydrogen site location: mixed
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F^2 > 2σ(F^2)] = 0.025	w = 1/[σ^2(Fo^2) + (0.033P)^2 + 0.2455P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.064	(Δ/σ)max = 0.001
S = 1.06	Δρmax = 0.22 e Å^−3
3002 reflections	Δρmin = −0.18 e Å^−3
221 parameters	Absolute structure: Flack x determined using 1154 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013)
0 restraints	Absolute structure parameter: 0.031 (7)
Primary atom site location: structure-invariant direct methods

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. All H atoms were located in difference maps and those on C atoms were treated thereafter as riding in geometrically idealized positions, with C—H = 0.95 Å for phenyl, 0.99 Å for CH₂ and 0.98 Å for methyl H atoms. The coordinates of the N—H and O—H H atoms were refined. The U_iso(H) values were assigned as 1.5U_eq of the attached atom methyl, OH, and ammonium H atoms, and as 1.2U_eq otherwise.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
S1	0.45672 (10)	0.72942 (4)	0.10139 (2)	0.01932 (13)
O1	0.6522 (3)	0.64462 (13)	0.60560 (7)	0.0234 (3)
H1OH	0.526 (6)	0.613 (2)	0.6171 (13)	0.035*
O2	1.2758 (2)	0.52566 (10)	0.29568 (6)	0.0150 (3)
O3	0.9501 (3)	0.54361 (10)	0.23911 (6)	0.0152 (3)
O4	0.8826 (2)	0.79919 (11)	0.28382 (6)	0.0159 (3)
N1	0.6958 (3)	0.65289 (13)	0.32141 (7)	0.0131 (3)
H1N	0.543 (5)	0.6144 (19)	0.3235 (10)	0.016*
N2	0.4517 (3)	0.90575 (13)	0.27842 (7)	0.0143 (3)
H21N	0.507 (5)	0.927 (2)	0.3129 (12)	0.022*
H22N	0.298 (5)	0.938 (2)	0.2718 (11)	0.022*
H23N	0.557 (5)	0.941 (2)	0.2526 (11)	0.022*
C1	0.6961 (4)	0.61434 (16)	0.55052 (9)	0.0177 (4)
C2	0.9078 (4)	0.65037 (18)	0.52474 (9)	0.0206 (4)
H2	1.0162	0.6960	0.5448	0.025*
C3	0.9612 (4)	0.61967 (16)	0.46948 (9)	0.0188 (4)
H3	1.1061	0.6452	0.4520	0.023*
C4	0.8066 (4)	0.55226 (16)	0.43912 (8)	0.0151 (4)
C5	0.5910 (4)	0.52002 (16)	0.46491 (9)	0.0183 (4)
H5	0.4796	0.4765	0.4444	0.022*
C6	0.5353 (4)	0.55030 (17)	0.52031 (9)	0.0193 (4)
H6	0.3874	0.5272	0.5374	0.023*
C7	0.8751 (4)	0.51252 (15)	0.38059 (9)	0.0153 (4)
H7A	0.7422	0.4661	0.3663	0.018*
H7B	1.0237	0.4679	0.3838	0.018*
C8	0.9225 (4)	0.60106 (15)	0.33686 (8)	0.0127 (4)
H8	1.0308	0.6558	0.3549	0.015*
C9	1.0589 (4)	0.55304 (14)	0.28579 (8)	0.0127 (4)
C10	0.6979 (3)	0.74683 (14)	0.29371 (8)	0.0117 (4)
C11	0.4474 (4)	0.78691 (14)	0.27481 (8)	0.0136 (4)
H11	0.3216	0.7592	0.3018	0.016*
C12	0.3816 (3)	0.75003 (16)	0.21469 (8)	0.0156 (4)
H12A	0.3336	0.6737	0.2163	0.019*
H12B	0.2376	0.7912	0.2017	0.019*
C13	0.5835 (4)	0.76236 (17)	0.17061 (8)	0.0171 (4)
H13A	0.7207	0.7137	0.1796	0.020*
H13B	0.6454	0.8368	0.1706	0.020*
C14	0.7332 (5)	0.7195 (2)	0.06034 (11)	0.0367 (6)
H14A	0.8149	0.7893	0.0596	0.055*
H14B	0.6935	0.6976	0.0215	0.055*
H14C	0.8415	0.6664	0.0776	0.055*
O1W	0.2853 (3)	0.50422 (12)	0.64496 (7)	0.0195 (3)
H1W	0.240 (5)	0.447 (2)	0.6281 (13)	0.029*
H2W	0.372 (6)	0.487 (2)	0.6762 (14)	0.029*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0240 (2)	0.0196 (2)	0.0143 (2)	−0.0005 (2)	−0.0008 (2)	−0.00063 (19)
O1	0.0273 (8)	0.0285 (8)	0.0144 (7)	−0.0058 (7)	0.0056 (7)	−0.0028 (6)
O2	0.0133 (7)	0.0133 (6)	0.0185 (7)	0.0011 (5)	0.0002 (6)	−0.0008 (6)
O3	0.0163 (7)	0.0156 (6)	0.0136 (6)	−0.0017 (6)	−0.0017 (6)	−0.0014 (5)
O4	0.0127 (7)	0.0136 (7)	0.0214 (7)	−0.0007 (5)	0.0007 (5)	0.0018 (5)
N1	0.0116 (8)	0.0115 (7)	0.0161 (8)	−0.0002 (7)	0.0001 (6)	0.0010 (6)
N2	0.0142 (8)	0.0134 (8)	0.0154 (8)	0.0014 (7)	0.0003 (7)	0.0010 (7)
C1	0.0229 (11)	0.0181 (10)	0.0123 (10)	0.0032 (8)	0.0012 (8)	0.0002 (8)
C2	0.0220 (11)	0.0228 (10)	0.0171 (10)	−0.0029 (9)	−0.0004 (9)	−0.0016 (8)
C3	0.0165 (9)	0.0229 (10)	0.0169 (10)	−0.0017 (9)	0.0018 (9)	0.0018 (8)
C4	0.0181 (10)	0.0133 (9)	0.0139 (10)	0.0042 (8)	0.0005 (8)	0.0038 (8)
C5	0.0210 (11)	0.0179 (9)	0.0160 (10)	−0.0031 (8)	−0.0017 (8)	0.0009 (8)
C6	0.0180 (10)	0.0226 (10)	0.0175 (10)	−0.0008 (9)	0.0023 (9)	0.0021 (8)
C7	0.0181 (10)	0.0120 (9)	0.0158 (10)	0.0015 (8)	0.0012 (8)	0.0017 (7)
C8	0.0141 (10)	0.0117 (8)	0.0124 (9)	0.0009 (8)	−0.0007 (8)	−0.0006 (7)
C9	0.0135 (9)	0.0076 (8)	0.0169 (10)	−0.0029 (8)	0.0000 (8)	0.0010 (7)
C10	0.0136 (9)	0.0109 (9)	0.0105 (9)	0.0012 (7)	0.0015 (7)	−0.0018 (7)
C11	0.0141 (9)	0.0122 (9)	0.0145 (9)	0.0001 (8)	0.0010 (8)	0.0019 (7)
C12	0.0149 (9)	0.0162 (9)	0.0158 (10)	−0.0023 (7)	−0.0025 (7)	0.0014 (8)
C13	0.0186 (10)	0.0177 (9)	0.0149 (10)	−0.0014 (8)	0.0012 (8)	−0.0016 (7)
C14	0.0377 (14)	0.0502 (16)	0.0222 (13)	0.0036 (13)	0.0064 (10)	−0.0097 (12)
O1W	0.0249 (8)	0.0188 (7)	0.0147 (7)	−0.0028 (6)	−0.0006 (6)	−0.0001 (6)

Geometric parameters (Å, º)

S1—C14	1.802 (3)	C5—C6	1.392 (3)
S1—C13	1.819 (2)	C5—H5	0.9500
O1—C1	1.372 (3)	C6—H6	0.9500
O1—H1OH	0.84 (3)	C7—C8	1.534 (3)
O2—C9	1.259 (3)	C7—H7A	0.9900
O3—C9	1.256 (2)	C7—H7B	0.9900
O4—C10	1.228 (2)	C8—C9	1.538 (3)
N1—C10	1.343 (2)	C8—H8	1.0000
N1—C8	1.448 (3)	C10—C11	1.528 (3)
N1—H1N	0.97 (3)	C11—C12	1.532 (3)
N2—C11	1.488 (2)	C11—H11	1.0000
N2—H21N	0.91 (3)	C12—C13	1.525 (3)
N2—H22N	0.95 (3)	C12—H12A	0.9900
N2—H23N	0.95 (3)	C12—H12B	0.9900
C1—C2	1.385 (3)	C13—H13A	0.9900
C1—C6	1.387 (3)	C13—H13B	0.9900
C2—C3	1.388 (3)	C14—H14A	0.9800
C2—H2	0.9500	C14—H14B	0.9800
C3—C4	1.392 (3)	C14—H14C	0.9800
C3—H3	0.9500	O1W—H1W	0.85 (3)
C4—C5	1.388 (3)	O1W—H2W	0.90 (3)
C4—C7	1.512 (3)
C14—S1—C13	100.05 (11)	N1—C8—C9	113.30 (16)
C1—O1—H1OH	109 (2)	C7—C8—C9	109.01 (15)
C10—N1—C8	120.38 (16)	N1—C8—H8	108.0
C10—N1—H1N	117.9 (14)	C7—C8—H8	108.0
C8—N1—H1N	120.5 (14)	C9—C8—H8	108.0
C11—N2—H21N	110.3 (16)	O3—C9—O2	125.79 (19)
C11—N2—H22N	113.9 (16)	O3—C9—C8	119.33 (17)
H21N—N2—H22N	109 (2)	O2—C9—C8	114.87 (17)
C11—N2—H23N	116.0 (16)	O4—C10—N1	124.39 (18)
H21N—N2—H23N	104 (2)	O4—C10—C11	120.75 (16)
H22N—N2—H23N	104 (2)	N1—C10—C11	114.86 (16)
O1—C1—C2	118.13 (19)	N2—C11—C10	107.23 (16)
O1—C1—C6	122.15 (19)	N2—C11—C12	110.91 (15)
C2—C1—C6	119.7 (2)	C10—C11—C12	112.47 (16)
C1—C2—C3	119.8 (2)	N2—C11—H11	108.7
C1—C2—H2	120.1	C10—C11—H11	108.7
C3—C2—H2	120.1	C12—C11—H11	108.7
C2—C3—C4	121.3 (2)	C13—C12—C11	115.31 (16)
C2—C3—H3	119.3	C13—C12—H12A	108.4
C4—C3—H3	119.3	C11—C12—H12A	108.4
C5—C4—C3	117.98 (19)	C13—C12—H12B	108.4
C5—C4—C7	120.98 (19)	C11—C12—H12B	108.4
C3—C4—C7	121.01 (19)	H12A—C12—H12B	107.5
C4—C5—C6	121.2 (2)	C12—C13—S1	108.02 (14)
C4—C5—H5	119.4	C12—C13—H13A	110.1
C6—C5—H5	119.4	S1—C13—H13A	110.1
C1—C6—C5	119.9 (2)	C12—C13—H13B	110.1
C1—C6—H6	120.1	S1—C13—H13B	110.1
C5—C6—H6	120.1	H13A—C13—H13B	108.4
C4—C7—C8	114.64 (16)	S1—C14—H14A	109.5
C4—C7—H7A	108.6	S1—C14—H14B	109.5
C8—C7—H7A	108.6	H14A—C14—H14B	109.5
C4—C7—H7B	108.6	S1—C14—H14C	109.5
C8—C7—H7B	108.6	H14A—C14—H14C	109.5
H7A—C7—H7B	107.6	H14B—C14—H14C	109.5
N1—C8—C7	110.24 (16)	H1W—O1W—H2W	110 (3)
O1—C1—C2—C3	178.66 (19)	C4—C7—C8—C9	163.90 (16)
C6—C1—C2—C3	−1.9 (3)	N1—C8—C9—O3	−13.3 (2)
C1—C2—C3—C4	−0.5 (3)	C7—C8—C9—O3	109.8 (2)
C2—C3—C4—C5	2.7 (3)	N1—C8—C9—O2	167.13 (16)
C2—C3—C4—C7	−175.37 (19)	C7—C8—C9—O2	−69.7 (2)
C3—C4—C5—C6	−2.7 (3)	C8—N1—C10—O4	−6.3 (3)
C7—C4—C5—C6	175.42 (19)	C8—N1—C10—C11	174.12 (16)
O1—C1—C6—C5	−178.65 (19)	O4—C10—C11—N2	−33.4 (2)
C2—C1—C6—C5	1.9 (3)	N1—C10—C11—N2	146.24 (16)
C4—C5—C6—C1	0.4 (3)	O4—C10—C11—C12	88.8 (2)
C5—C4—C7—C8	123.7 (2)	N1—C10—C11—C12	−91.57 (19)
C3—C4—C7—C8	−58.3 (3)	N2—C11—C12—C13	74.5 (2)
C10—N1—C8—C7	165.36 (17)	C10—C11—C12—C13	−45.6 (2)
C10—N1—C8—C9	−72.2 (2)	C11—C12—C13—S1	−173.31 (13)
C4—C7—C8—N1	−71.1 (2)	C14—S1—C13—C12	−167.63 (16)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N···O2^i	0.97 (3)	1.95 (3)	2.863 (2)	156 (2)
N2—H21N···O1W^ii	0.91 (3)	2.01 (3)	2.805 (2)	145 (2)
N2—H22N···O3^iii	0.95 (3)	1.91 (3)	2.827 (2)	162 (2)
N2—H23N···O2^iv	0.95 (3)	1.80 (3)	2.743 (2)	171 (2)
C6—H6···O1W	0.95	2.61	3.290 (3)	129
C11—H11···O1^v	1.00	2.66	3.359 (2)	127
C11—H11···O4^i	1.00	2.49	3.108 (2)	119
C12—H12A···O2^i	0.99	2.65	3.440 (2)	137
C13—H13B···O2^iv	0.99	2.53	3.472 (2)	159
O1W—H1W···S1^vi	0.85 (3)	2.54 (3)	3.3674 (16)	165 (3)
O1W—H2W···O3^vii	0.90 (3)	1.82 (3)	2.716 (2)	179 (3)

Symmetry codes: (i) x−1, y, z; (ii) x+1/2, −y+3/2, −z+1; (iii) −x+1, y+1/2, −z+1/2; (iv) −x+2, y+1/2, −z+1/2; (v) x−1/2, −y+3/2, −z+1; (vi) −x+1/2, −y+1, z+1/2; (vii) −x+3/2, −y+1, z+1/2.