. 2004 Feb 20;101(9):2823–2827. doi: 10.1073/pnas.0308295100

Table 1. Examples of the most dramatic variations in the extent of desolvation of backbone hydrogen bonds for the same folding domains examined across different species.

Protein or domain	Species/PDB code	G, Mb	N	N_HB	ρ	Y	r_d/HB (×100)
DHFR	Haloferax volcanii (archaea)/1vdr	≈1.8	157	82	21.84	4	4.8
DHFR	Thermotoga maritima (bacteria)/1dlg	1.8	164	87	21.78	5	5.7
DHFR	E. coli/1dra	4.6	159	84	21.11	5	5.9
DHFR	Lactobacillus casei/3dfr		162	90	19.62	11	12.2
DHFR	H. sapiens/1hfp	≈3,000	186	95	18.21	16	16.8
Ankyrin repeat	M. musculus (mouse)/lap7	≈3,000	168	77	17.08	11	14.3
Ankyrin repeat	H. sapiens/1bd8	≈3,000	156	88	16.72	16	18.2
Cytochrome c	Chlamydomonas reinhardtii (algae)/1cyi	≈100	89	52	19.74	6	11.5
Cytochrome c	Rhodopila globiformis (bacteria)/1hro		105	50	17.52	7	14.0
Cytochrome c	Oryza sativa (rice)/1ccr	430	111	55	14.94	11	20.0
Cytochrome c	Thunnus alalunga (tuna)/5cyt		103	53	14.25	13	24.5
Cytochrome c	Katsuo (bonito)/1cyc		103	41	14.03	12	29.2
Cytochrome c	Equus caballus/1giw	≈3,000	104	44	14.01	14	31.8
Hemoglobin	Vitreoscilla stercoraria (bacteria)/2vhb	≈4	136	102	23.50	0	0
Hemoglobin	Lupinus luteus (pea)/1gdj		153	109	23.43	0	0
Hemoglobin	Paramecium caudatum/1dlw		116	77	22.02	0	0
Hemoglobin	(Nonsymbiotic) Oryza sativa (rice)/1d8u	430	165	106	23.58	2	1.8
Hemoglobin	Equus caballus/1gob	≈3,000	146	101	21.45	2	2.0
Hemoglobin	H. sapiens/1bz0	≈3,000	146	103	21.45	3	2.9
Hsp90 chaperone	Saccharomyces cerevisiae (yeast)/1amw	12.1	213	147	20.07	20	13.6
Hsp90 chaperone	H. sapiens/1byq	≈3,000	213	139	19.37	26	18.7
Lysozyme	Coliphage T4 (phage)/109L	4–5	160	120	18.68	18	15.0
Lysozyme	Gallus gallus (hen egg white)/132L		129	85	17.42	19	22.3
Lysozyme	Canis familiaris/1ell	≈3,000	130	90	17.34	20	22.2
Lysozyme	H. sapiens/133L	≈3,000	130	86	16.38	29	33.7
Myoglobin	Aplysia limacina (mollusc)/1mba		146	106	23.42	0	0
Myoglobin	Chironomus thummi thummi (insect)/1eca	≈200	136	101	21.31	3	2.9
Myoglobin	Thunnus albacares (tuna)/1myt		146	110	21.15	8	7.2
Myoglobin	Caretta caretta (sea turtle)/1lht		153	110	21.09	11	10.0
Myoglobin	Physeter catodon (whale)/1bz6		153	113	20.98	11	9.7
Myoglobin	Sus scrofa (pig)/1mwc	≈2,700	153	113	19.95	12	10.6
Myoglobin	Equus caballus/1dwr	≈3,000	152	112	18.90	14	12.5
Myoglobin	Elephas maximus (Asian elephant)/1emy		153	115	18.90	15	13.0
Myoglobin	Phoca vitulina (seal)/1mbs		153	109	18.84	16	14.7
Myoglobin	H. sapiens/2hbc	≈3,000	146	102	18.80	16	15.7
PDZ	Drosophila melanogaster/1ihj	137	94	47	17.88	3	6.4
PDZ	Rattus norvegicus/1qlc	≈3,000	95	41	17.80	8	19.5
PDZ	H. sapiens/1g90	≈3,000	91	44	16.29	9	20.4
PrP^c	S. cerevisiae/1koa	12.1	233	148	22.33	13	8.7
PrP^c	S. cerevisiae/1kod	12.1	220	137	22.95	10	7.3
PrP^c	M. musculus/1ag2	≈3,000	103	53	12.42	29	54.7
PrP^c	Mesocricetus auratus (Syrian hamster)/1b10		104	59	11.79	35	59.3
PrP^c	Bos taurus/1dwy	≈3,000	104	59	11.76	35	59.3
PrP^c	H. sapiens/1qm0	≈3,000	104	59	11.71	35	59.3
Reverse transcriptase	Moloney murine leukemia virus/1mml	≈10^-2	251	158	19.71	12	7.6
Reverse transcriptase	HIV-1 (RT domains 1,2)/1rth	≈10^-2	209	120	16.68	21	17.5
SH3	C. elegans (worm)/3sem	97	57	31	18.48	1	3.2
SH3	Gallus gallus/1hd3		58	29	18.40	2	6.9
SH3	H. sapiens/5hck	≈3,000	61	24	16.74	4	16.6
Ubiquitin	E. coli/1foz	4.6	66	39	18.69	4	10.2
Ubiquitin	M. musculus/1u9b	≈3,000	158	104	18.54	19	18.2
Ubiquitin	H. sapiens/1ubi	≈3,000	76	48	16.56	9	18.7

The notations are as follows: G, estimated genome size when known; N, polypeptide chain length; N_HB, total no. of backbone hydrogen bonds; ρ, no. of desolvating carbonaceous groups per backbone hydrogen bond averaged over all hydrogen bonds in protein structure; Y, total no. of dehydrons in the structure; and r_d/HB(×100), percentage ratio of dehydrons (no. of dehydrons every hundred hydrogen bonds).