會(huì)員.png)
QQ交談
您所在位置：請(qǐng)輸入產(chǎn)品關(guān)鍵字：
郵編：200431
聯(lián)系人：王小姐
電話：021-56640936
傳真：021-33250231
手機(jī)：13122441390 15900755943
留言：發(fā)送留言
個(gè)性化：www.shifengsj.com
網(wǎng)址：www.shfeng-edu.com
商鋪：http://true-witness.com/st236594/
Rules of siRNA
最近更新時(shí)間：2016-1-21
提 供 商：上海士鋒生物科技有限公司資料大小：50.6KB
文件類型：PNG 圖片下載次數(shù)：263次
資料類型：未知文件瀏覽次數(shù)：1172次
General guidelines
siRNA targeted sequence is usually 21 nt in length. Avoid regions within 50-100 bp of the start codon and the termination codon Avoid intron regions Avoid stretches of 4 or more bases such as AAAA, CCCC Avoid regions with GC content <30% or > 60%. Avoid repeats and low complex sequence Avoid single nucleotide polymorphism (SNP) sites Perform BLAST homology search to avoid off-target effects on other GENEs or sequences Always design negative controls by scrambling targeted siRNA sequence. The control RNA should have the same length and nucleotide composition as the siRNA but have at least 4-5 bases mismatched to the siRNA. Make sure the scrambling will not create new homology to other genes.
Tom Tuschl"s rules
Select targeted region from a given cDNA sequence beginning 50-100 nt downstream of start condon First search for 23-nt sequence motif AA(N19). If no suitable sequence is found, then, Search for 23-nt sequence motif NA(N21) and convert the 3" end of the sense siRNA to TT Or search for NAR(N17)YNN Target sequence should have a GC content of around 50%
Rational siRNA design
By experimentally analyzing the silencing efficiency of 180 siRNAs targeting the mRNA of two genes and correlating it with various sequence features of individual siRNAs, Reynolds et al at Dharmacon, Inc identified eight characteristics associated with siRNA functionality. These characteristics are used by rational siRNA design algorithm to evaluate potential targeted sequences and assign scores to them. Sequences with higher scores will have higher chance of success in RNAi. The table below lists the 8 criteria and the methods of score assignment.
Criteria
Description
Score
Yes
No
1
Moderate to low (30%-52%) GC Content
1 point
2
At least 3 A/Us at positions 15-19 (sense)
1 point /per A or U
3
Lack of internal repeats (Tm*<20¡ãC)
1 point
4
A at position 19 (sense)
1 point
5
A at position 3 (sense)
1 point
6
U at position 10 (sense)
1 point
7
No G/C at position 19 (sense)
-1 point
8
No G at position 13 (sense)
-1 point
A sum score of 6 defines the cutoff for selecting siRNAs. All siRNAs scoring higher than 6 are acceptable candidates.