You can label your peptide with FITC or TRITC, and it will be fluorescent.

Commercial peptide suppliers can incorporate any of a number of fluorescent labels during the synthesis, either at the N-terminus or at an internal Lys or Cys residue. Additionally, tryptophan is naturally fluorescent, with UV excitation.

It is possible, but it is more expensive than expression of protein, but the purity in this case will be wery high. Using attached label (Julio A Camarero) is optimal variant in my view. Cost is depend on amount, length and purity of peptide. How much of peptide do you need? What is the purpose of your research?

Thank you all, so it seems there isn't any distinct "sequences" with specific excitation and emission wavelength?

I don't know such peptides with ordinary amino acids.  Maybe green fluorescent protein will be good for you http://www.conncoll.edu/ccacad/zimmer/GFP-ww/GFP-1.htm 

Green fluorescent protein and its relatives have an intrinsic fluorophore formed spontaneously by a chemical reaction from its own amino acid sequence and buried within the protein. I do not know of any short peptides that have an intrinsic fluorophore other than tryptophan. Tyrosine is also weakly fluorescent.

Here is an overview of amino acid fluorescence:

http://www.biotek.com/resources/articles/peptides-amino-acids-fluorescence.html

Synthesizing through SPPS (Solid Phase Peptide Synthesis), the short-length fluorescence peptide, incorporating the suggested AA [Amino Acid(s)] will be a better option. The starting raw materials (suitably protected AAs, coupling reagents and synthesis-grade anhydrous solvents) can be had from standard vendors. The simplest of the protocols are available online. One can also order different CRO (Contact Research Organization) for that too for a price. The immunologist/microbiologist are also synthesizing the sequences, one need not be a chemist to assemble the sequence through SPPS!

From Sigma/Adrich catalog

250 mg FITC,  $60

10 mg TRITC, $200

FITC will give you green fluorescence, excitation around 490 nm

TRITC (mroe expensive) will give you red fluorescence, excitation around 530 nm.

Thank you Julio, Adam, Riaz & Alexander for your time and attention to this matter. 

I don't know if this will provide you with any more help but I just thought I'd give you some advice anyway, maybe it will help you in some way!

I synthesise peptides using SPPS and have labelled many of them with FITC. This has worked perfectly each time, only do keep in mind that labelling your peptide with FITC is altering the peptide's chemical nature. Also, FITC is very bulky, and depending on the side chains/R groups of the last amino acid of the chain (before FITC is added) sterics may hinder the reactions progress (and therefore overall yield).

Before I couple FITC, I couple a linker (aminohexanoic acid) to the last amino acid and then I couple FITC, to give the reaction some "space" to occur!

Other than that, synthesising a fluorescent peptide using SPPS is easily done and with great yields, once the peptide isn't overly long (more than 20AA)

I hope this helps, and best of luck!

Dear Michelle, many thanks for your kind answer.