Plasmid Miniprep Kit offers a simple, rapid, and cost-effective method for isolating plasmid DNA from recombinant E. coli cultures. By combining silica-binding technology and the convenience of a spin column format, up to 15 µg of high copy plasmid DNA can be recovered from 1–5 ml of E. coli culture in less than 30 minutes. Note that actual yield and optimal volume of culture to use depend on the plasmid and the culture medium (see Procedure, step 1). An overnight recombinant E. coli culture is harvested with centrifugation and subjected to a modified alkaline-SDS lysis procedure followed by adsorption of the DNA onto silica in the presence of high salts.1,2 Contaminants are then removed by a spin-wash step. Finally, the bound DNA is eluted in water or Tris-EDTA buffer. The recovered plasmid DNA is predominately in its supercoiled form. There is no visual evidence of genomic DNA or RNA contamination detected by agarose gel electrophoresis. The DNA is ready for immediate use in downstream applications such as restriction digestion, ligation, sequencing, PCR, and transfection.
Universal Total RNA Purification Kit provides a rapid method for the isolation and purification of total RNA from cultured animal cells, tissue samples, blood, plasma, serum, bacteria, yeast, fungi, plants, and viruses. The kit purifies all sizes of RNA, from large mRNA and ribosomal RNA down to microRNA (miRNA) and small interfering RNA (siRNA). The RNA is preferentially purified from other cellular components such as proteins, without the use of phenol or chloroform. The purified RNA is of the highest integrity, and can be used in a number of downstream applications including real time PCR, reverse transcription PCR, Northern blotting, RNase protection and primer extension, and expression array assays. Purification is based on spin column chromatography using a proprietary resin as the separation matrix. The RNA is preferentially purified from other cellular components such as proteins without the use of phenol or chloroform. The process involves first lysing the cells or tissue of interest with the provided Buffer RL (Figure 1 on page 3). Ethanol is then added to the lysate, and the solution is loaded onto a spin-column. The resin binds RNA in a manner that depends on ionic concentrations. Thus only the RNA will bind to the column, while the contaminating proteins will be removed in the flowthrough or retained on the top of the resin. The bound RNA is then washed with the provided Wash Solution A in order to remove any remaining impurities, and the purified total RNA is eluted with the Elution Solution A. The purified RNA is of the highest integrity, and can be used in a number of downstream applications.
Immunoglobulins (Igs) are produced by B lymphocytes and secreted into plasma. The Ig molecule in monomeric form is a glycoprotein with a molecular weight of approximately 150 kDa that is shaped more or less like a Y. Basic structure of the Ig monomer (Figure 1) consists of two identical halves connected by two disulfide bonds. Each half is made up of a heavy chain of approximately 50 kDa and a light chain of approximately 25 kDa, joined together by a disulfide bond near the carboxyl terminus of the light chain. The heavy chain is divided into an Fc portion, which is at the carboxyl terminal (the base of the Y), and a Fab portion, which is at the amino terminal (the arm of the Y). Carbohydrate chains are attached to the Fc portion of the molecule. The Fc portion of the Ig molecule is composed only of heavy chains. Fc regions of IgG and IgM can bind to receptors on the surface of immunomodulatory cells such as macrophages and stimulate the release of cytokines that regulate the immune response. The Fc region contains protein sequences common to all Igs as well as determinants unique to the individual classes. These regions are referred to as the constant regions because they do not vary significantly among different Ig molecules within the same class. The Fab portion of the Ig molecule contains both heavy and light chains joined together by a single disulfide bond. One heavy and one light chain pair combine to form the antigen binding site of the antibody. Each Ig monomer is capable of binding two antigen molecules.