The use of computer animation in chemistry is rapidly growing, both for research and for education. This symposium brings together for the first time the diverse group working in the field, in hopes of nucleating communication. Those involved include chemists, physicists, and biologists. The common pattern which runs through their work is the use of computers to create visual images illustrating chemical structures and processes.
The accompanying test run displays some important structural features of myoglobin, a very large molecule which is a protein active in supplying oxygen to muscle tissue. All proteins are made up of sub-units called amino acids, of which myoglobin has 153 connected into one continuous chain which folds around into a box-like superstructure. The film begins by showing the 3-dimensional arrangement of the amino acids in myoglobin by building the chain one link at a time (the amino acids are represented by a single blue circle in the position of the alpha carbon). The completed chain, called the backbone, is then rotated to show its structure.
We next display a structural feature found in many proteins and particularly prevalent in myoglobin, the alpha helix, in which a section of the chain winds into a coil - a girder which gives the box rigidity. The helix is separated from the rest of the molecule and its bonding displayed. The red groups are peptide bonds which join the amino acids in all of myoglobin but which, for simplicity, were earlier represented by straight blue lines. The yellow bonds are hydrogen bonds between atoms of the peptide bonds, which serve to hold the chain in its helical conformation. The green structures are the remaining part of the amino acids called the residues. The residues, like the peptide bonds, were omitted earlier for simplicity.
The alpha helix is then returned to its place in the backbone and the three components of the active site (the raison d'etre of this protein) are added one at a time. First, two important residues (histidines) appear in green. They help to support the iron-containing meme group, which next appears in red. The iron (solid red) of the meme and histidines hold the oxygen, which appears in a yellow ball. The entire structure is then rotated.
We next zoom in on the active site to show the bonding of the iron and oxygen in detail. The iron is octahedrally coordinated, bonded to the four planar nitrogens of the pentagonal pyrrole groups and also bonded above and below to oxygen and one of the histidine side chains. The oxygen is held by electrostatic bonds to the iron and the other histidine. The meme group itself is an interesting structure and is now rotated to display its planar, very symmetric form. We then climb back out of myoglobin and view it rotating.
A Protein Primer is a production of The Senses Bureau, a group of students under the leadership of Professor Kent Wilson at the University of California at San Diego. The director of the film is Bob Weiss, the cinematographer is Noel Bartlett, and the programmers are Watie Alberty, Fred Heidrich, and Charles Morgan. The images were generated on a magnetic tape by a CDC 3600 computer using the program ORTEP from Oak Ridge Laboratories. A separate tape was written for each of the four colors used. The tapes were then processed using a 35mm pin-registered camera attached to a DatagraphiX 4060 provided by DatagraphiX of San Diego to produce four black-and-white strips of film {Kodak Recordak Dacomatic), which were overlayed through filters onto a single 16mm master at Cinema Research, Inc. of Los Angeles. The sound track, composed by Gino Piserchio on a computer of sorts - the Moog Synthesizer, was then added on optically at Hollywood Film Enterprises.