Melittin Protein

Interactive model, with minimal support

Overview and Learning Objectives

Users can explore the hydrophobicity of the amino acids in Melittin, and can see its behavior in water and oil.

The purpose of this activity is to explore the connection between the shape of melittin and two possible environments, water and oil, and to learn about its connection with bee venom.

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Classroom Practice

http://www.concord.org/~barbara/workbench_web/unitV/melittin.html

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Central Concepts

Key Concept:

Melittin is a lethal small protein that makes up a good part of bee venom. Its effect is due to the needle-like shape it assumes in water, enabling it to puncture cell membranes.

Additional Related Concepts

Molecular Biology

• Mellitin
• Membrane pore
• Membrane potential
• Protein
• Protein Function
• Protein structure

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Textbook References

• Biology (Miller and Levine) Prentice Hall 5th Edition - Unit 2: Chapter 7 - Nucleic Acids and Protein Synthesis

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Extensions and Connections

1. Also look at a better structural view. http://www.doe-mbi.ucla.edu/People/Eisenberg/Gallery/Mellitin.html
2. Read a great description of the process: "Although they employ strikingly different weapons to get there, all venoms have the same basic target: the cell membrane, a two-layer wrapping around all biological cells. It consists largely of proteins and fatty phospholipids. The phospholipids are ingenious molecules with a bulbous head that's attracted to water and a fatty-acid tail that can't stand the stuff. So the phospholipids of the outer layer naturally line up side by side, their heads all pointed outward to bask in the great liquid sea of life. The phospholipids of the inner layer line up the other way, with their tails pointing toward the tails of the outer layer and their heads facing the calm inner sea of the cell. This makes for a very stable two-layer membrane, with a water-resistant fatty-acid middle that keeps the cell as snug as a house that's wrapped in Tyvek and R-19 insulation. Then the honeybee's venom bursts in, bent on havoc. A peptide called mellitin strikes the opening blow, shouldering in among the closely packed phospholipids of the cell membrane. This throws open the door to a powerful enzyme in the venom, phospholipase A, which rushes in and severs the connection between the head and tail of the phospholipid. The membrane begins to break apart. If the victim of this attack is a red blood cell, hemoglobin spills out in a widening stream until the entire cell dissolves. If the victim is a neuron, damage to the membrane upsets the delicate relationship between the ions inside and outside the cell, causing the neuron to fire little jolts of pain, called action potentials, over and over." (http://www.discover.com/issues/jun-03/features/featstung/)
3. Read more about bee venom: http://www.chemsoc.org/exemplarchem/entries/2001/loveridge/index-page8.html

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Activity Credits

Created by CC Project: Molecular Workbench using Molecular Workbench

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Requirements

• Java 1.5+ - Java 1.5+ is available for Windows, Linux, and Mac OS X 10.4 and greater. If you are using Mac OS X 10.3, you can download MW Version 1.3 and explore within it instead.

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