Sample preparation is one of the most variable and time-consuming steps in the analysis of proteins by MS, and the quality and reproducibility of sample extraction and preparation significantly impact the results. Occasionally, additional steps are required to improve sample quality, including digestion and recovery of peptide fragments from SDS-PAGE gels, or peptide guanidination to improve sequence coverage. Each kit has been optimized to produce high quality peptide digests for dependable proteomics analysis using mass spectrometry.

Pierce In-Solution Tryptic Digestion and Guanidination Kit
The Pierce In-Solution Tryptic Digestion and Guanidination Kit provides an optimized procedure and reagents for approximately 90 digests, each containing 0.025 to 10 μg of protein.

• Complete digestion—trypsin completely digests protein ranging from 0.025 to 10 μg (∼90 reactions)
• Specific—guanidination reaction produces little to no N-terminal modification
• Convenient—kit includes reagents for digestion, reduction, alkylation, and guanidination
• Efficient—protein can be digested and guanidinated in a single day

Trypsin specifically cleaves peptide bonds at the carboxyl side of arginine and lysine residues. The signals from the arginine-containing peptides are generally stronger, due to the more basic side chain. To enhance overall ionization, guanidination converts lysines to homoarginines and is specific for the amine of lysine, but may occur minimally at the amine of the peptide's N-terminus. This derivatization leads to an increase in the intensity of the lysine-containing peptides and improved sequence coverage overall.

Pierce In-Gel Tryptic Digestion Kit
The Pierce In-Gel Tryptic Digestion Kit provides a complete set of reagents for performing approximately 150 digestions on colloidal Coomassie- or fluorescent dye-stained protein bands. The kit includes modified porcine trypsin, de-staining buffers, reduction reagents, alkylation reagents, and digestion buffers, along with detailed and simple instructions.

• Complete—includes all necessary reagents for gel destaining, reduction, alkylation, and tryptic digestion of proteins
• Robust—optimized procedure and reagents produce reliable digestions and data generation using a wide range of conditions
• Specific—contains highly purified and modified MS-grade trypsin with no chymotryptic activity and minimal autolytic activity

Two key sample preparation steps are the complete digestion of proteins into peptides and subsequent concentration and clean-up of peptides for mass spectrometry analysis. The Pierce In-Gel Tryptic Digestion Kit accomplishes the first of these steps for protein samples extracted from gel slices. Pierce C-18 Spin Columns and Tips accomplish the second step to clean-up the sample to be MS-ready.