Dear Md Hasif Sinha thank you for this interesting technical question. Please see the first answer in the following closely related RG thread entitled

Which reducing agent do you prefer?

https://www.researchgate.net/post/Which_reducing_agent_do_you_prefer

It is stated here that "TCEP has the advantage over DTT and B-ME that it does not reduce metals as easily as the other two."

Interested

One uses TCEP when carrying out maleimide-based conjugation at protein SH groups. TCEP keeps the protein reduced while not interfering with the reaction.

Dear Md Hasif Sinha thank you agin for your interesting technical question. In this context please also have a look at the following useful link:

TCEP HCL VS. DTT

https://agscientific.com/blog/2019/04/side-by-side-comparison-dtt-vs-tcep-preferred-reducing-agents/

It is stated here that "TCEP HCl has the advantages of being odorless, more powerful, irreversible, more hydrophilic, and more resistant to oxidation in air. Near complete reduction of disulfide bonds."

TCEP reduces without using a thiol group. Therefore using it for, for instance, dye labeling of the Cysteine thiolate makes sure the reducer (TCEP) will not be dye labeled. In fact, adding excess of bME or DTT in the end of such a labeling reaction, terminates it by labeling the bME or DTT via its thiol with the leftover free dye.

Thanks, dear Professor Frank T. Edelmann for your valuable reply.