Team:TU-Delft/Protocol 9

Our project deals with E.coli cells which sense Auto-inducing peptides (AIPs) from the Staphylococcus aureus and starts producing Antimicrobial peptides in order to kill the Staphylococcus aureus. Different protocols used during the project are described below.

• Transforming Parts from Distribution kit
• Growing the Single Colonies from the Agar Plates
• Making glycerol stocks
• Miniprep Protocol
• Restriction digestion
• Ligation
• Gel Extraction Procedure
• PCR Purification
• Tricine Gels

Tricine Gels

Tricine Gels are ideal for peptides and low molecular weight proteins (less than 10 kDa). The Tricine Gels are based on the Tricine system developed by (Schaegger and vonJagow, 1987). In this buffer system, tricine substitutes glycine in the running buffer resulting in more efficient stacking and destacking of low molecular weight proteins and higher resolution of smaller peptides. Tricine gels must be used with denatured or reduced proteins only. The separating range of Tricine gels is 2.5-200 kDa.

Requirements:

1. Protein sample
2. Deionized water
3. Low molecular weight Protein markers
4. Tricine SDS Sample Buffer (Given cross refernce)
5. Reducing Agent for reduced samples (Optional)
6. Tricine SDS Running Buffer (Given cross refernce)

Preparing samples

The Tricine SDS Sample Buffer (2X) and Reducing Agent (10X) are available from Life Technologies (Invitrogen).

1. Prepare reduced or non-reduced samples for Tricine gels as described below:

Note:For reduced sample, add the reducing agent immediately prior to electrophoresis to obtain the best results.

Reagent	Reduced Sample	Non-reduced Sample
Sample	x µL	x µL
Tricine SDS Sample Buffer (2X)
Reducing Agent (10X)	1 µL	-
Deionized Water	to 4 µL	to 5 µL
Total Volume	10 µL	10 µL



2. Heat samples at 85℃ for 2 minutes. Load the sample immediately on the gel.

Preparing Running Buffer

1. Prepare 1000 ml of 1X Tricine SDS Running Buffer using Tricine SDS Running Buffer (10X) as follows:
   Tricine SDS Running Buffer (10X)     100 ml Deionized Water     900 ml Total Volume     1000 ml
2. Mix thoroughly. Use this buffer to fill the Upper and Lower Buffer Chambers of the XCell SureLock. Mini-Cell for electrophoresis.

Tricine SDS Sample Buffer (2X)

450 mM Tris HCl
12% Glycerol
4% SDS
0.0025% Coomassie® Blue G
0.0025% Phenol Red
pH 8.45

1. To prepare 10 ml of 2X Tricine SDS Sample Buffer, mix the following reagents:
   • 3 M Tris HCl, pH 8.45    3 ml
   • Glycerol     2.4 ml
   • SDS     0.8 g
   • 0.1% Coomassie® Blue G     0.5 ml
   • 0.1% Phenol Red     0.5 ml
2. Mix well and adjust the volume to 10 ml with ultrapure water.
3. . Store at +4℃. The buffer is stable for 6 months when stored at +4C.