+b=[]
+newchain=True
+if os.path.exists('plik.pdb'):
+ with open('plik.pdb') as f:
+ for line in f:
+ if line[0:4]=='ATOM' and line[13:15]=='CA':
+# print line
+ if newchain or int(line[22:26])>ires:
+ b.append(math.sqrt(float(line[60:66])*3/8/math.pi/math.pi))
+ ires=int(line[22:26])
+ newchain=False
+ if line[0:3]=='TER':
+ newchain=True
+ if line[0:3]=='END':
+ break
+
+
+