The Protein Man's Blog | A Discussion of Protein Research

How much biotin is coupled to my protein? The HABA/Avidin Assay

Posted by Protein Man on Oct 17, 2017 2:30:00 PM

Biotin, a 244 Dalton molecule, exhibits an extraordinary binding affinity for avidin and streptavidin (Ka=1015 M-1). This high binding affinity means that proteins, particularly antibodies, are routinely labeled with biotin.  The labeled proteins can now be rapidly purified with avidin and streptavidin resins or detected with streptavidin and avidin coupled to enzyme reporters, such as HRP (horseradish peroxidase.

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Topics: Protein Labeling

Sputum Processing, from viscous mucus to homogenous samples

Posted by Protein Man on Oct 10, 2017 2:32:00 PM

Sputum Liquefaction: from viscous, heterogeneous mucus to equivalent, homogenous samples

Sputum processing has one main purpose; to render the viscous, heterogeneous specimen to a homogenous state (evenly distributed suspension). This homogenous suspension will be dispensed into multiple aliquots for cryopreservation, smear microscopy, gram stain, and culture. Each aliquot should be representative of the original specimen. This can be accomplished through the process of sputum liquefaction.

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Topics: Sample Clean Up

Role of reporter genes to assay for transcription factors & more

Posted by Protein Man on Oct 3, 2017 2:30:00 PM

Reporter Gene Assays and their applications

Reporter gene assays are paramount for study of regulation of gene expression by gene regulatory elements (cis-acting factors), transcription factors or exogenous regulators (trans-acting factors). In reporter gene assays, the activity of a reporter gene is measured. A reporter gene is joined to a target regulatory DNA sequence in an expression vector, which is then transfected into the cell type of choice. The reporter gene is transcribed and translated in the cells and its activity is measured to access the strength or function of the target regulatory DNA sequence or study effects of transcription factors or potential drugs etc.

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Topics: Cytotoxicity Assays

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