L-(+)-Cysteine

CAS Registry Number®

52-90-4

CAS Name

L-(+)-Cysteine

Molecular Formula

C3H7NO2S

Molecular Mass

121.16

Cite this Page

L-(+)-Cysteine.   CAS Common Chemistry.   CAS, a division of the American Chemical Society, n.d.   http://commonchemistry.cas.org/ChemicalDetail.aspx?ref=52-90-4 (retrieved 2025-07-18) (CAS RN: 52-90-4).  Licensed under the Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0).

Compound Properties

  • Melting Point (1)

    240 °C (decomp)

  • Density (2)

    1.6666 g/cm³ @ Temp: 45.00 °C

Source(s)

Other Names and Identifiers

InChI

InChI=1S/C3H7NO2S/c4-2(1-7)3(5)6/h2,7H,1,4H2,(H,5,6)/t2-/m0/s1

InChIKey

InChIKey=XUJNEKJLAYXESH-REOHCLBHSA-N

SMILES

[C@@H](C(O)=O)(CS)N

Canonical SMILES

O=C(O)C(N)CS

Other Names for this Substance

  • L-Cysteine
  • Cysteine, L-
  • Half-cystine
  • β-Mercaptoalanine
  • Thioserine

View All

Deleted or Replaced CAS Registry Numbers

4371-52-2, 154605-72-8, 1404190-35-7