(2S)-2-[[(2S)-2-[[(2S)-2-[[2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-6-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-amino-3-(4-hydroxyphenyl)propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]hexanoyl]amino]propanoyl]amino]-4-methylpentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]-4-methylpentanoyl]amino]acetyl]amino]-3-methylbutanoyl]amino]propanoyl]amino]propanoic acid

C98H171N37O26 — CID 127043567

About (2S)-2-[[(2S)-2-[[(2S)-2-[[2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-6-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-amino-3-(4-hydroxyphenyl)propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]hexanoyl]amino]propanoyl]amino]-4-methylpentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]-4-methylpentanoyl]amino]acetyl]amino]-3-methylbutanoyl]amino]propanoyl]amino]propanoic acid

(2S)-2-[[(2S)-2-[[(2S)-2-[[2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-6-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-amino-3-(4-hydroxyphenyl)propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]hexanoyl]amino]propanoyl]amino]-4-methylpentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]-4-methylpentanoyl]amino]acetyl]amino]-3-methylbutanoyl]amino]propanoyl]amino]propanoic acid (PubChem CID 127043567) has the molecular formula C98H171N37O26 and a molecular weight of 2283.68 g/mol. Its IUPAC name is (2S)-2-[[(2S)-2-[[(2S)-2-[[2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-6-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-amino-3-(4-hydroxyphenyl)propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]hexanoyl]amino]propanoyl]amino]-4-methylpentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]-4-methylpentanoyl]amino]acetyl]amino]-3-methylbutanoyl]amino]propanoyl]amino]propanoic acid.

Molecular Properties

• Compound Name: (2S)-2-[[(2S)-2-[[(2S)-2-[[2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-6-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-amino-3-(4-hydroxyphenyl)propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]hexanoyl]amino]propanoyl]amino]-4-methylpentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]-4-methylpentanoyl]amino]acetyl]amino]-3-methylbutanoyl]amino]propanoyl]amino]propanoic acid
• PubChem CID: 127043567
• Molecular Formula: C98H171N37O26
• Molecular Weight: 2283.68 g/mol
• Exact Mass: 2282.32
• IUPAC Name: (2S)-2-[[(2S)-2-[[(2S)-2-[[2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-6-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-amino-3-(4-hydroxyphenyl)propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]hexanoyl]amino]propanoyl]amino]-4-methylpentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]-4-methylpentanoyl]amino]acetyl]amino]-3-methylbutanoyl]amino]propanoyl]amino]propanoic acid
• SMILES: [H]/N=C(/N)NCCC[C@H](NC(=O)[C@H](C)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@H](CCCN/C(N)=N/[H])NC(=O)[C@H](C)NC(=O)[C@H](C)NC(=O)[C@H](C)NC(=O)[C@H](CCCN/C(N)=N/[H])NC(=O)[C@H](C)NC(=O)[C@@H](N)Cc1ccc(O)cc1)C(=O)N[C@@H](C)C(=O)N[C@@H](CCCCN)C(=O)N[C@@H](C)C(=O)N[C@@H](CC(C)C)C(=O)N[C@@H](C)C(=O)N[C@@H](CCCN/C(N)=N/[H])C(=O)N[C@@H](CCC(N)=O)C(=O)N[C@@H](CC(C)C)C(=O)NCC(=O)N[C@H](C(=O)N[C@@H](C)C(=O)N[C@@H](C)C(=O)O)C(C)C
• InChI: InChI=1S/C98H171N37O26/c1-45(2)41-68(84(150)115-44-72(139)135-73(47(5)6)93(159)124-50(9)76(142)125-57(16)94(160)161)134-91(157)67(33-35-71(102)138)132-90(156)65(27-22-40-114-98(109)110)130-81(147)55(14)123-92(158)69(42-46(3)4)133-82(148)56(15)121-85(151)61(23-17-18-36-99)126-79(145)53(12)120-87(153)63(25-20-38-112-96(105)106)128-80(146)54(13)122-88(154)66(32-34-70(101)137)131-89(155)64(26-21-39-113-97(107)108)129-77(143)51(10)117-74(140)48(7)116-75(141)49(8)119-86(152)62(24-19-37-111-95(103)104)127-78(144)52(11)118-83(149)60(100)43-58-28-30-59(136)31-29-58/h28-31,45-57,60-69,73,136H,17-27,32-44,99-100H2,1-16H3,(H2,101,137)(H2,102,138)(H,115,150)(H,116,141)(H,117,140)(H,118,149)(H,119,152)(H,120,153)(H,121,151)(H,122,154)(H,123,158)(H,124,159)(H,125,142)(H,126,145)(H,127,144)(H,128,146)(H,129,143)(H,130,147)(H,131,155)(H,132,156)(H,133,148)(H,134,157)(H,135,139)(H,160,161)(H4,103,104,111)(H4,105,106,112)(H4,107,108,113)(H4,109,110,114)/t48-,49-,50-,51-,52-,53-,54-,55-,56-,57-,60-,61-,62-,63-,64-,65-,66-,67-,68-,69-,73-/m0/s1
• InChIKey: NXUWTKIOMJSLSV-DEEZXRHXSA-N
• XLogP: -12.18
• TPSA: 1054.45 Ų
• H-Bond Donors: 39
• H-Bond Acceptors: 31
• Rotatable Bonds: 76
• Heavy Atoms: 161
• Complexity: —

Lipinski Rule of Five

3 violations

Rule	Value
MW ≤ 500	2283.68
LogP ≤ 5	-12.18
H-Bond Donors ≤ 5	39
H-Bond Acceptors ≤ 10	31

Computed Properties (RDKit)

• Structural Alerts: {'alert_name': 'Aliphatic_long_chain', 'substructure': 'N/A'}, {'alert_name': 'imine_1', 'substructure': 'N/A'}, {'alert_name': 'imine_2', 'substructure': 'N/A'}

Frequently Asked Questions

What is the IUPAC name of (2S)-2-[[(2S)-2-[[(2S)-2-[[2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-6-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-amino-3-(4-hydroxyphenyl)propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]hexanoyl]amino]propanoyl]amino]-4-methylpentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]-4-methylpentanoyl]amino]acetyl]amino]-3-methylbutanoyl]amino]propanoyl]amino]propanoic acid?

The IUPAC name of (2S)-2-[[(2S)-2-[[(2S)-2-[[2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-6-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-amino-3-(4-hydroxyphenyl)propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]hexanoyl]amino]propanoyl]amino]-4-methylpentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]-4-methylpentanoyl]amino]acetyl]amino]-3-methylbutanoyl]amino]propanoyl]amino]propanoic acid (CID 127043567) is (2S)-2-[[(2S)-2-[[(2S)-2-[[2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-6-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-amino-3-(4-hydroxyphenyl)propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]hexanoyl]amino]propanoyl]amino]-4-methylpentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]-4-methylpentanoyl]amino]acetyl]amino]-3-methylbutanoyl]amino]propanoyl]amino]propanoic acid.

What is the SMILES notation for (2S)-2-[[(2S)-2-[[(2S)-2-[[2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-6-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-amino-3-(4-hydroxyphenyl)propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]hexanoyl]amino]propanoyl]amino]-4-methylpentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]-4-methylpentanoyl]amino]acetyl]amino]-3-methylbutanoyl]amino]propanoyl]amino]propanoic acid?

The canonical SMILES for (2S)-2-[[(2S)-2-[[(2S)-2-[[2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-6-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-amino-3-(4-hydroxyphenyl)propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]hexanoyl]amino]propanoyl]amino]-4-methylpentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]-4-methylpentanoyl]amino]acetyl]amino]-3-methylbutanoyl]amino]propanoyl]amino]propanoic acid is [H]/N=C(/N)NCCC[C@H](NC(=O)[C@H](C)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@H](CCCN/C(N)=N/[H])NC(=O)[C@H](C)NC(=O)[C@H](C)NC(=O)[C@H](C)NC(=O)[C@H](CCCN/C(N)=N/[H])NC(=O)[C@H](C)NC(=O)[C@@H](N)Cc1ccc(O)cc1)C(=O)N[C@@H](C)C(=O)N[C@@H](CCCCN)C(=O)N[C@@H](C)C(=O)N[C@@H](CC(C)C)C(=O)N[C@@H](C)C(=O)N[C@@H](CCCN/C(N)=N/[H])C(=O)N[C@@H](CCC(N)=O)C(=O)N[C@@H](CC(C)C)C(=O)NCC(=O)N[C@H](C(=O)N[C@@H](C)C(=O)N[C@@H](C)C(=O)O)C(C)C.

What is the InChIKey of (2S)-2-[[(2S)-2-[[(2S)-2-[[2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-6-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-amino-3-(4-hydroxyphenyl)propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]hexanoyl]amino]propanoyl]amino]-4-methylpentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]-4-methylpentanoyl]amino]acetyl]amino]-3-methylbutanoyl]amino]propanoyl]amino]propanoic acid?

The InChIKey is NXUWTKIOMJSLSV-DEEZXRHXSA-N. The full InChI is InChI=1S/C98H171N37O26/c1-45(2)41-68(84(150)115-44-72(139)135-73(47(5)6)93(159)124-50(9)76(142)125-57(16)94(160)161)134-91(157)67(33-35-71(102)138)132-90(156)65(27-22-40-114-98(109)110)130-81(147)55(14)123-92(158)69(42-46(3)4)133-82(148)56(15)121-85(151)61(23-17-18-36-99)126-79(145)53(12)120-87(153)63(25-20-38-112-96(105)106)128-80(146)54(13)122-88(154)66(32-34-70(101)137)131-89(155)64(26-21-39-113-97(107)108)129-77(143)51(10)117-74(140)48(7)116-75(141)49(8)119-86(152)62(24-19-37-111-95(103)104)127-78(144)52(11)118-83(149)60(100)43-58-28-30-59(136)31-29-58/h28-31,45-57,60-69,73,136H,17-27,32-44,99-100H2,1-16H3,(H2,101,137)(H2,102,138)(H,115,150)(H,116,141)(H,117,140)(H,118,149)(H,119,152)(H,120,153)(H,121,151)(H,122,154)(H,123,158)(H,124,159)(H,125,142)(H,126,145)(H,127,144)(H,128,146)(H,129,143)(H,130,147)(H,131,155)(H,132,156)(H,133,148)(H,134,157)(H,135,139)(H,160,161)(H4,103,104,111)(H4,105,106,112)(H4,107,108,113)(H4,109,110,114)/t48-,49-,50-,51-,52-,53-,54-,55-,56-,57-,60-,61-,62-,63-,64-,65-,66-,67-,68-,69-,73-/m0/s1.

What are the key properties of (2S)-2-[[(2S)-2-[[(2S)-2-[[2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-6-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-amino-3-(4-hydroxyphenyl)propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]hexanoyl]amino]propanoyl]amino]-4-methylpentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]-4-methylpentanoyl]amino]acetyl]amino]-3-methylbutanoyl]amino]propanoyl]amino]propanoic acid?

(2S)-2-[[(2S)-2-[[(2S)-2-[[2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-6-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-amino-3-(4-hydroxyphenyl)propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]hexanoyl]amino]propanoyl]amino]-4-methylpentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]-4-methylpentanoyl]amino]acetyl]amino]-3-methylbutanoyl]amino]propanoyl]amino]propanoic acid has a molecular weight of 2283.68 g/mol, XLogP of -12.18, 76 rotatable bonds, 39 hydrogen bond donors, and 31 hydrogen bond acceptors.

Where does this data come from?

All data for (2S)-2-[[(2S)-2-[[(2S)-2-[[2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-6-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-amino-3-(4-hydroxyphenyl)propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]propanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]propanoyl]amino]hexanoyl]amino]propanoyl]amino]-4-methylpentanoyl]amino]propanoyl]amino]-5-carbamimidamidopentanoyl]amino]-5-oxopentanoyl]amino]-4-methylpentanoyl]amino]acetyl]amino]-3-methylbutanoyl]amino]propanoyl]amino]propanoic acid is sourced from PubChem (CID 127043567), the world's largest open chemistry database maintained by the National Library of Medicine (NIH).