认为执行您的方法时存在拼写错误或错误的 url - 将 url 更改为http://www.uniprot.org/uniprot/P28653_PGS1_MOUSE,您将获得一个包含两个元素的列表,您可以通过循环或直接访问这些元素,例如lst[1]获取序列。
代码
import requests
from bs4 import BeautifulSoup as bs
r = requests.get('http://www.uniprot.org/uniprot/P28653_PGS1_MOUSE')
soup = bs(r.content, 'html.parser')
lst = soup.find_all('pre')
print(lst)
输出
[<pre>>sp|P28653|PGS1_MOUSE Biglycan OS=Mus musculus OX=10090 GN=Bgn PE=1 SV=1
MCPLWLLTLLLALSQALPFEQKGFWDFTLDDGLLMMNDEEASGSDTTSGVPDLDSVTPTF
SAMCPFGCHCHLRVVQCSDLGLKTVPKEISPDTTLLDLQNNDISELRKDDFKGLQHLYAL
VLVNNKISKIHEKAFSPLRKLQKLYISKNHLVEIPPNLPSSLVELRIHDNRIRKVPKGVF
SGLRNMNCIEMGGNPLENSGFEPGAFDGLKLNYLRISEAKLTGIPKDLPETLNELHLDHN
KIQAIELEDLLRYSKLYRLGLGHNQIRMIENGSLSFLPTLRELHLDNNKLSRVPAGLPDL
KLLQVVYLHSNNITKVGINDFCPMGFGVKRAYYNGISLFNNPVPYWEVQPATFRCVTDRL
AIQFGNYKK
</pre>, <pre class="sequence"> 10 20 30 40 50<br/>MCPLWLLTLL LALSQALPFE QKGFWDFTLD DGLLMMNDEE ASGSDTTSGV <br/> 60 70 80 90 100<br/>PDLDSVTPTF SAMCPFGCHC HLRVVQCSDL GLKTVPKEIS PDTTLLDLQN <br/> 110 120 130 140 150<br/>NDISELRKDD FKGLQHLYAL VLVNNKISKI HEKAFSPLRK LQKLYISKNH <br/> 160 170 180 190 200<br/>LVEIPPNLPS SLVELRIHDN RIRKVPKGVF SGLRNMNCIE MGGNPLENSG <br/> 210 220 230 240 250<br/>FEPGAFDGLK LNYLRISEAK LTGIPKDLPE TLNELHLDHN KIQAIELEDL <br/> 260 270 280 290 300<br/>LRYSKLYRLG LGHNQIRMIE NGSLSFLPTL RELHLDNNKL SRVPAGLPDL <br/> 310 320 330 340 350<br/>KLLQVVYLHS NNITKVGIND FCPMGFGVKR AYYNGISLFN NPVPYWEVQP <br/> 360 <br/>ATFRCVTDRL AIQFGNYKK <br/></pre>]