1 minute to know | How to determine protein preparation difficulty: cysteine
Introduction
?In the field of scientific research and pharmaceutical R&D, it is often necessary to prepare some proteins. Before protein preparation, a series of analytical work needs to be carried out in order to select an appropriate preparation protocol and thus improve the success rate of preparation. Protein analysis usually starts from the species, type, structure, physicochemical and biochemical properties of the protein. At present, there is no exact standard for judging the difficulty of protein preparation. To this end, we extracted data on 56,547 proteins from 7 mammals (Human, Mouse, Rat, Rabbit, Bovine, Pig, Sumatran orangutan) from the Uniprot database, and analyzed information such as the number of amino acids, cysteine, and cysteine percentage at the amino acid level, aiming to provide scientists with reference for judging the difficulty of protein preparation.
After analyzing and processing these data, we classified proteins that meet any of the following criteria as ‘difficult to prepare proteins’: the number of amino acids is less than 100 or greater than 1000; the number of cysteine is greater than or equal to 12 or the percentage of cysteine is greater than 4.0%. The specific analysis is as follows:
Number of amino acids
We counted 56,547 proteins, with a total of 29,793,248 amino acids, and an average of 527 amino acids per protein.
The distribution of the number of amino acids is shown in Figure 1, and the range of amino acid proteins number and the percentages are shown in Table 1.
Cysteine number and distribution
According to data analysis, each protein contains 12 cysteine on average, and the number of proteins containing 0-12 cysteine accounts for 69.51%.
The distribution of cysteine number is shown in Figure 2, the distribution of cysteine percentage is shown in Figure 3, and the table of cysteine percentage is shown in Table 2.
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Brief summary
Obtained by analyzing data from 56,547 proteins from 7 mammals on Uniprot:
l? Number of amino acids in protein: the average number of amino acids per protein is 527, and 86.22% of the proteins have amino acids in the range of 101-1000;
l? Number of cysteine: Each protein contains 11.75 cysteine on average, of which 69.51% contain 0-12 cysteine;
l? Cysteine percentage: 88.18% of proteins have cysteine percentages in the range of 0-4.0%.
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Based on the above data and analysis, we identify proteins that meet any of the following properties as a protein with high preparation difficulty: