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Fitness

Problem

Phospholipase A2 (PLA2) proteins are major components of snake venoms. When an animal is bitten by a venomous snake, these PLA2 enzymes catalyze the breakdown of phospholipids and can disrupt cell membranes, leading to muscle damage and other effects. Snake venoms often contain multiple types of PLA2 proteins, each with a slightly different amino acid sequence.
The pit viper Protobothrops flavoviridis contains multiple PLA2 enzymes, including BP-I and BP-II. The amino acid sequences of BP-I and BP-II differ by only one amino acid. A group of scientists tested the enzymatic activity of BP-I and BP-II over a range of concentrations. Their results are shown in Figure 1.
The y axis on the line graph is labeled enzyme activity and the x axis is labeled enzyme concentration. There are no marked intervals on either axis. The key for the graph is a solid line represents BP-II and the dotted line represents BP-I. The BP-II line on the graph begins at the origin of the x and y axis and extends upward in a diagonal line. The BP-I dotted line on the graph begins at the origin of the x and y axis, and remains on a horizontal plane along the x axis and at the start of the x axis until the line reaches the far end of the x axis. At that point the dotted line rises sharply at a nearly vertical angle.
Figure 1. Enzymatic activity of BP-I and BP-II over a range of enzyme concentrations.
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