What is "dithreitol"?

The article by Hu et al. [[1](https://doi.org/10.1177/154405910608501212)] mentions a compound "*dithreitol*" in the *Saliva Proteome Analysis* section (emphasis mine):



> 
> For the "shotgun" approach, saliva samples (1 mL) were pre-fractionated with the use of Millipore ultracentrifuge filters (Millipore Corp., Billerica, MA, USA).
>  Individual fractions were treated with 10 mM **dithreitol** for 30 min and then 50 mM iodoacetamide for 30 min.
> 
> 
> 


[PubChem](https://pubchem.ncbi.nlm.nih.gov/#query=dithreitol) doesn't reveal any details as to what this compound exactly is and suggests alternative spelling, e.g. [D-threitol](https://pubchem.ncbi.nlm.nih.gov/compound/169019).


[Google Books search](https://www.google.com/search?hl=en&tbm=bks&q=%22dithreitol%22) results in several mentions of this compound in the literature, but I didn't find any further details except that it's probably a [sulfhydryl reagent](https://books.google.com/books?id=7JcnWmCB7EIC&q="dithreitol"&dq="dithreitol"&hl=en&redir_esc=y).
This makes me think that "*dithreitol*" could be another name for [dithiothreitol](https://en.wikipedia.org/wiki/Dithiothreitol), but I didn't manage to find any solid references to support this proposition.


To sum it up: what is *dithreitol*, exactly, and what chemical and structural formulas does it posses?


### References


1. Hu, S.; Li, Y.; Wang, J.; Xie, Y.; Tjon, K.; Wolinsky, L.; Loo, R. R. O.; Loo, J. A.; Wong, D. T. Human Saliva Proteome and Transcriptome. *J Dent Res* **2006**, 85 (12), 1129–1133. DOI: [10.1177/154405910608501212](https://doi.org/10.1177/154405910608501212).





> 
> For the "shotgun" approach, saliva samples ($\pu{1 mL}$) were pre-fractionated with the use of Millipore ultracentrifuge filters (Millipore Corp., Billerica, MA, USA). Individual fractions were treated with $\pu{10 mM}$ dithreitol for $\pu{30 min}$, and then $\pu{50 mM}$ iodoacetamide for $\pu{30 min}$.
> 
> 
> 


This reaction sequence in Ref.1 has a clear intention: First, break disulfide bonds in saliva proteins using a thiol exchanging reagent and then trap the recently formed thiol groups by iodoacetamide (Ref.2). According to Ref.2:



> 
> Alkylation of cysteine thiols with iodo, bromo or chloro substituted acetic acid or acetamide is a classic approach that has been exploited since the 1930′s.
> 
> 
> 


Thus, it is safe to assume that this second reaction is intended to trap thiol group as quickly as possible (The relative reaction rates between glutathione and these halogenated acetates are $100:60:1$ for iodo-, bromo- and chloro-acetates respectively; Ref.3). 


Also keep in mind that disulfide reduction to corresponding thiol is accomplished primarily by thiol exchange type reagents such as dithiothreitol (DTT) or 2-mercaptoethanol (ME). Thus, it is also safe to assume that dithreitol mentioned in Ref.1 is definitely a thiol exchanging reagent, possibly DTT. Therefore, I think it is a chain mistake as M. Farooq suggested in his comment. 


**References:**


1. S. Hu, Y. Li, J. Wang, Y. Xie, K. Tjon, L. Wolinsky, R. R. O. Loo, J. A. Loo, D. T. Wong, "Human Saliva Proteome and Transcriptome," *J. Dent. Res.* **2006**, *85(12)*, 1129–1133 (DOI: 10.1177/154405910608501212).
2. Jakob R. Winther, Colin Thorpe, "Quantification of Thiols and Disulfides," *Biochimica et Biophysica Acta* **2014**, *1840(2)*, 838-846 (<https://doi.org/10.1016/j.bbagen.2013.03.031>).
3. Frank Dickens, "CLII. Interaction of halogenacetates and SH compounds. The reaction of halogenacetic acids with glutathione and cysteine. The mechanism of iodoacetate poisoning of glyoxalase," *Biochem J.* **1933**, *27(4)*, 1141–1151 (doi: 10.1042/bj0271141).


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