D-Cysteine

Also known as: (S)-2-Amino-3-mercaptopropionic acid, (2S)-2-amino-3-mercaptopropanoic acid, H-D-Cys-OH, D-Cystein, MFCD00066461, EINECS 213-062-0, β-Mercaptoalanine

D-Cysteine (CAS 921-01-7) is a compound in the Organic Acids category listed in the Jingsj chemical database. It has the molecular formula C3H7NO2S and a molecular weight of 121.16 g/mol. Key properties include a melting point of 230ºC, a boiling point of 293.9±35.0 °C at 760 mmHg, a density of 1.3±0.1 g/cm3 and a flash point of 131.5±25.9 °C. It is classified under GHS with signal word Warning and hazard statements H302 — Harmful if swallowed. It is listed by 1 supplier, from 4.40 to 5.50 CNY. Record last updated Aug 21, 2026.

CAS No.: 921-01-7
Jingsj CID: J-1112681-0
Molecular Formula: C₃H₇NO₂S
Molecular Weight: 121.16 g/mol
Category: Organic Acids
Last updated: 8/21/2026

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Supplier	Purity / Pack	Base Price	Unit Price	Origin
Maikuo Made to Order	99% 500g	¥2,200.00	$0.66 /gBest ¥4.40/g CNY	CN China MOQ 500g	View Product
Maikuo Made to Order	99% 100g	¥550.00	$0.82 /g ¥5.50/g CNY	CN China MOQ 100g	View Product

Physicochemical Properties

Melting Point	230ºC
Boiling Point	293.9±35.0 °C at 760 mmHg
Density	1.3±0.1 g/cm3
Flash Point	131.5±25.9 °C
Exact Mass	121.019745
PSA	102.12000
LogP	0.23
Vapor Pressure	0.0±1.3 mmHg at 25°C
Refractive Index	1.550
SMILES	C([C@H](C(=O)O)N)S
InChIKey	XUJNEKJLAYXESH-UWTATZPHSA-N
InChI	1S/C3H7NO2S/c4-2(1-7)3(5)6/h2,7H,1,4H2,(H,5,6)/t2-/m1/s1

GHS Safety & Compliance

IrritantSignal word: Warning

H302 — Harmful if swallowed

Activity & Biological Data

Target	Human Endogenous Metabolite
Additional Information	[1]. Seki T. Availability of D-cysteine as a protectant for cerebellar neurons. Nihon Yakurigaku Zasshi. 2019;154(3):133-137. [2]. Soutourina J, et al. Role of D-cysteine desulfhydrase in the adaptation of Escherichia coli to D-cysteine. J Biol Chem. 2001 Nov 2;276(44):40864-72. [3]. Guo X1, et al. Effect of D-cysteine on dual-species biofilms of Streptococcus mutans and Streptococcus sanguinis. Sci Rep. 2019 Apr 30;9(1):6689.

Target

Human Endogenous Metabolite

Additional Information

[1]. Seki T. Availability of D-cysteine as a protectant for cerebellar neurons. Nihon Yakurigaku Zasshi. 2019;154(3):133-137. [2]. Soutourina J, et al. Role of D-cysteine desulfhydrase in the adaptation of Escherichia coli to D-cysteine. J Biol Chem. 2001 Nov 2;276(44):40864-72. [3]. Guo X1, et al. Effect of D-cysteine on dual-species biofilms of Streptococcus mutans and Streptococcus sanguinis. Sci Rep. 2019 Apr 30;9(1):6689.

Customs & Trade Information

HS Code	29309013

Frequently Asked Questions

What is the CAS number of D-Cysteine?

The CAS number of D-Cysteine is 921-01-7.

What are the molecular formula and molecular weight of D-Cysteine?

D-Cysteine has molecular formula C3H7NO2S and molecular weight 121.16 g/mol.

Which suppliers offer D-Cysteine?

1 supplier(s) listed; reference unit price ¥4.40–5.50 /g.

Is D-Cysteine hazardous?

D-Cysteine has GHS signal word Warning and hazard statements H302 — Harmful if swallowed.

Data compiled from public chemical databases such as PubChem and supplier catalogs; supplier offers are provided by suppliers.

Last updated: 8/21/2026

How to cite: Jingsj. "D-Cysteine (CAS 921-01-7)". Jingsj Chemical Database. https://www.jingsj.com/compound/J-1112681-0 (accessed 2026-11-06).

Data for reference only; verify product details with suppliers before purchase.