Python_Selecting最长的AA序列

Question

我有以下序列，我试图选择最长的序列。我知道它是第一个序列，但是如何告诉Python选择M（start）和*（stop）之间距离最长的序列？

First= MATVEPETTPTPNPPTTEEEKTESNQEVANPEHYIKHPLQNRWALWFFKNDKSKTWQANLRLISKFDTVEDFWALYNHIQLSSNLMPGCDYSLFKDGIEPMWEDEKNKRGGRWLITLNKQQRRSDLDRFWLETLLCLIGESFDDYSDDVCGAVVNVRAKGDKIAIWTTECENREAVTHIGRVYKERLGLPPKIVIGYQSHADTATKSGSTTKNRFVV*  
Second= WRLSNRKPPLLLIPRLQKRRKRNLIRRLLTQNTILNIPYRTDGHSGFLKMIKAKLGKQTCG*SPSLILLKTFGLCTTISSCLVI*CLAVTTHFLRMVLSLCGKMRKTNGEDDG*LH*TNSRDEVTSIAFG*RHFCALLENLLMTTVMMYVALLLMLELKVIR*QYGLLNVKTEKLLHI*GGYTRKG*DFLQR**LVISPTQTQLLRAAPPLKIGLLF  
Third= GDCRTGNHPYS*SPDYRRGENGI*SGGC*PRTLY*TSPTEQMGTLVF*K**KQNLASKPAADLQV*YC*RLLGSVQPYPVV**FNAWL*LLTF*GWY*AYVGR*EKQTGRTMANYIEQTAETK*PRSLLARDTSVPYWRIF**LQ**CMWRCC*C*S*R**DSNMDY*M*KQRSCYTYREGIQGKVRTSSKDSDWLSVPRRHSY*ERLHH*K*VCCL  
Fourth= LNNKPIFSGGAALSSCVCVGLITNHYLWRKS*PFLVYPPYMCNSFSVFTFSSPYCYLITFSSNINNSATYIITVVIKRFSNKAQKCL*PKAIEVTSSLLFVQCN*PSSSPFVFLIFPHRLNTILKK*VVTARH*ITRQLDMVVQSPKVFNSIKLGDQPQVCLPSFAFIIFKKPECPSVL*GMFNIVFWVSNLLIRFRFLLFCSRGIRSRGGFRFDSRH  
Fifth= *TTNLFLVVEPLLVAVSAWD**PITIFGGSPNLSLYTLPICVTASLFSHSVVHIAILSPLALTLTTAPHTSSL*SSKDSPIRHRSVSSQKRSRSLRLCCLFNVISHRPPRLFFSSSHIGSIPSLKSE*SQPGIKLLDNWIWLYRAQKSSTVSNLEISRRFACQVLLLSFLKNQSAHLFCRGCLI*CSGLATS*LDSVFSSSVVGGLGVGVVSGSTVA  
Sixth= KQQTYF*WWSRS**LCLRGTDNQSLSLEEVLTFPCIPSLYV*QLLCFHIQ*SILLSYHL*L*H*QQRHIHHHCSHQKILQ*GTEVSLAKSDRGHFVSAVCSM*LAIVLPVCFSHLPT*AQYHP*KVSSHSQALNY*TTGYGCTEPKSLQQYQTWRSAAGLLAKFCFYHF*KTRVPICSVGDV*YSVLG*QPPD*IPFSPLL*SGD*E*GWFPVRQSP 

Answer 1

为了让您一开始，这里有一些基本的命令，让你感兴趣的长度。我定义的检查发现每个字符的第一要素之间的长度的函数。

First= 'MATVEPETTPTPNPPTTEEEKTESNQEVANPEHYIKHPLQNRWALWFFKNDKSKTWQANLRLISKFDTVEDFWALYNHIQLSSNLMPGCDYSLFKDGIEPMWEDEKNKRGGRWLITLNKQQRRSDLDRFWLETLLCLIGESFDDYSDDVCGAVVNVRAKGDKIAIWTTECENREAVTHIGRVYKERLGLPPKIVIGYQSHADTATKSGSTTKNRFVV*' 
Second= 'WRLSNRKPPLLLIPRLQKRRKRNLIRRLLTQNTILNIPYRTDGHSGFLKMIKAKLGKQTCGSPSLILLKTFGLCTTISSCLVICLAVTTHFLRMVLSLCGKMRKTNGEDDGLHTNSRDEVTSIAFGRHFCALLENLLMTTVMMYVALLLMLELKVIRQYGLLNVKTEKLLHIGGYTRKGDFLQR**LVISPTQTQLLRAAPPLKIGLLF' 
Third= 'GDCRTGNHPYSSPDYRRGENGISGGCPRTLYTSPTEQMGTLVFKKQNLASKPAADLQVYCRLLGSVQPYPVVFNAWLLLTFGWYAYVGREKQTGRTMANYIEQTAETKPRSLLARDTSVPYWRIFLQCMWRCCCS*R**DSNMDYMKQRSCYTYREGIQGKVRTSSKDSDWLSVPRRHSYERLHHK*VCCL' 
Fourth= 'LNNKPIFSGGAALSSCVCVGLITNHYLWRKSPFLVYPPYMCNSFSVFTFSSPYCYLITFSSNINNSATYIITVVIKRFSNKAQKCLPKAIEVTSSLLFVQCNPSSSPFVFLIFPHRLNTILKKVVTARHITRQLDMVVQSPKVFNSIKLGDQPQVCLPSFAFIIFKKPECPSVLGMFNIVFWVSNLLIRFRFLLFCSRGIRSRGGFRFDSRH' 
Fifth= '*TTNLFLVVEPLLVAVSAWD**PITIFGGSPNLSLYTLPICVTASLFSHSVVHIAILSPLALTLTTAPHTSSLSSKDSPIRHRSVSSQKRSRSLRLCCLFNVISHRPPRLFFSSSHIGSIPSLKSESQPGIKLLDNWIWLYRAQKSSTVSNLEISRRFACQVLLLSFLKNQSAHLFCRGCLICSGLATSLDSVFSSSVVGGLGVGVVSGSTVA' 
Sixth= 'KQQTYF*WWSRS**LCLRGTDNQSLSLEEVLTFPCIPSLYVQLLCFHIQSILLSYHLLHQQRHIHHHCSHQKILQGTEVSLAKSDRGHFVSAVCSMLAIVLPVCFSHLPTAQYHPKVSSHSQALNYTTGYGCTEPKSLQQYQTWRSAAGLLAKFCFYHFKTRVPICSVGDVYSVLGQPPDIPFSPLLSGDE*GWFPVRQSP' 

def sequence_length(string, char1, char2): 
    try: 
     return string.index(char2) - string.index(char1) 
    except ValueError: 
     return None 

print(sequence_length(First, 'M', '*')) 
print(sequence_length(Second, 'M', '*')) 
print(sequence_length(Third, 'M', '*')) 
print(sequence_length(Fourth, 'M', '*')) 
print(sequence_length(Fifth, 'M', '*')) 
print(sequence_length(Sixth, 'M', '*')) 

返回此：

217 
135 
98 
None 
None 
-89