Gelatin Veronal Buf With EDTA (GVBE)

Specifications

• Name: GVBE (GVBo with EDTA)
• Composition: 0.1 % gelatin, 5 mM Veronal, 145 mM NaCl, 0.025 % NaN3, 10 mM EDTA, pH 7.3.
• Form: Liquid
• Preservative: Sterile filtered with 0.025% sodium azide as a bactericidal agent
• Storage: +4oC. Avoid freezing which causes gelatin to gel. If frozen, do not microwave or heat the buffer on a hot plate instead heat the buffer in a water bath at 100 oC to redissolve gelatin.
• Precautions: Azide is poisonous to all living organisms.

Detailed description

General Description

GVBE is an isotonic buffer used in complement assays to prevent complement activation or to stop ongoing complement activation when added at the end of an incubation.

Buffer Components

EDTA is used in this buffer to chelate calcium and magnesium and thereby inhibit complement activation by all three pathways. Veronal is used as the buffer because in the mid-1900s this was the only buffer for pH range 7.2-7.4 that did not chelate metal ions and did not inhibit complement reactions as did other buffers. Sodium chloride is present to provide an isotonic environment so that cells do not lyse due to osmotic pressure. Gelatin is present to prevent loss of protein components due to adsorption onto tips or tubes during dilutions and in the assays themselves. Azide is present to prevent bacterial growth.

Physical Characteristics

The concentration of gelatin in this buffer is below the concentration that forms solid gels. However, because of the gelatin is close to its gelling concentration at 4oC some strings of gelatin form during standing at this temperature. They can be redissolved easily by heating to 37oC or by brief heating in a microwave oven.

Applications

GVBE is often used as the buffer added at the end of an assay to stop complement activation and dilute the reaction to levels that can be read spectrophotometrically. It is also used in setting up control assays where no complement activation should occur (background control assays).