Counting the Dead...Faster

Apoptosis, or programmed cell death, is a hot topic. In this publication alone, more than 14 articles mentioning apoptosis have been published within the past year. It is therefore little wonder that new kits for apoptosis detection seem to be introduced on a daily basis. One of the most popular methods for detecting apoptosis is the caspase activity assay. Caspases are cellular enzymes that, when activated, initiate a proteolytic cascade that ultimately leads to apoptosis; caspases are thus use

Nov 26, 2001
Aileen Constans
Apoptosis, or programmed cell death, is a hot topic. In this publication alone, more than 14 articles mentioning apoptosis have been published within the past year. It is therefore little wonder that new kits for apoptosis detection seem to be introduced on a daily basis. One of the most popular methods for detecting apoptosis is the caspase activity assay. Caspases are cellular enzymes that, when activated, initiate a proteolytic cascade that ultimately leads to apoptosis; caspases are thus useful markers for apoptosis.1

Madison, Wis.-based Promega Corp.'s latest offering in this field is the Apo-ONE™ Homogeneous Caspase-3/7 Assay, a kit that, as its name suggests, detects caspase-3 and -7 activity in cell culture. The assay employs a substrate, Z-DEVD-Rhodamine 110, which fluoresces upon cleavage by caspase-3/7; the amount of fluorescence is proportional to the amount of caspase activity present in the sample. The system includes a proprietary lysis/activity buffer that allows one-step, or homogeneous, detection of caspase activity, unlike currently available kits that require multiple steps. "That's one of the key factors that pharmaceutical companies are looking for in their screening applications," explains product manager Pam Guthmiller. "The fewer steps they have in their screening applications, the more cost- effective it is for them to screen multiple compounds," she says. Furthermore, reducing the number of steps produces a faster assay: Apo-ONE can provide results in as little as one hour. Finally, the assay kit offers increased sensitivity; according to company literature, a single assay can detect caspase activity in as few as 400 cells in a 96-well format. Because the assay requires only one step and is easily scalable, it is especially suited for automation and high-throughput screening.

--Aileen Constans (aconstans@the-scientist.com)
1. J. Cortese, "Death watch II: Caspases and apoptosis," The Scientist, 15[13]:24, June 25, 2001.
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