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Proteins
1. Focus on proteins Page 3
Materials
Figure 3.
Proteins can provide many useful materials.		 1.4 Proteins put to work
We can use proteins as useful materials as well as for food. For example, the protein in animal hide is processed to make leather. Silk is a protein made by the silkworm.

Scientists have recently developed techniques that allow them to use micro-organisms to produce proteins in relatively large quantities. Scientists can use a remarkable refinement of the technique to make changes to the sequence of a-amino acids in the proteins. Proteins can now be redesigned to perform new and different tasks. This area of work is called protein engineering. Although still in its early stages, protein engineering already provides improved methods for diagnosing and treating some medical conditions. You can read more about protein engineering in Chapter 4.

Spiders'silk
Next time you see a spider’s web, take a closer look before you brush it away. We all know that silkworms are valued for the fibres they spin, but spiders are doing much the same thing.

Spiders’ webs and silk from silkworms are both made from protein material called fibroin. Silkworms and spiders hold concentrated solutions of the protein in glands inside their bodies. They squirt this out through narrow openings, forming thin filaments that ¢ dry’ very quickly. The solutions have concentrations of between 15% and 30% so crystallise easily, but only outside the creature. The squirting process forces the molecules to line up so they pack together in crystalline fibres.

Different creatures produce different types of fibroin. Individual creatures can also tailor fibres to suit different purposes by changing the make up of their fibroin. Cocoon silk is more stretchy than the silk used in webs. The silk used in webs is stronger than steel of the same diameter.

Protein is a valuable commodity. Spiders recycle it by eating the silk wrapping along with the prey trapped inside.
Spiders' web
Spiders make their webs from concentrated protein solution.
Unilever Education Advanced Series: Proteins
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