Table 1.
Unfolding forces of stable structural segments
| Secondary structurea | Structural segmentb | Polypeptide segment (aa)c | Average contour length ± SD (aa)d | Average unfolding force ± SD (pN)a | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ZnCl2 (μm) | ZnCl2 (μm) | 1 mm EDTA | 200 μm CaCl2 | 200 μm CdCl2 | 200 μm CoCl2 | ||||||||||
| 0f | 200 | 0f | 10 | 25 | 50 | 100 | 200 | 400 | |||||||
| N-terminal region | N1 | 20-26 | 19 ± 2 | 19 ±2 | 131 ± 38
(106) |
109 ± 37
(117) |
108 ± 31
(141) |
129 ± 43
(122) |
134 ± 40
(93) |
130 ± 39
(63) |
130 ± 39
(76) |
116 ± 33
(65) |
109 ± 30 (51) | 125 ± 39 (56) | 104 ± 28
(62) |
| N-terminal region | N2 | 27-37 | 26 ± 2 | 27 ± 2 | 139 ± 38
(121) |
121 ± 36
(117) |
120 ± 38
(128) |
151 ± 51
(138) |
147 ± 43
(89) |
152 ± 40
(67) |
139 ± 41
(81) |
126 ± 32
(70) |
125 ± 37
(57) |
125 ± 40
(58) |
112 ± 28
(59) |
| Helix I | H1 | 38-60 | 37 ± 3 | 37 ± 3 | 132 ± 46
(116) |
124 ± 38
(122) |
124 ± 41
(121) |
155 ± 49
(136) |
146 ± 50
(98) |
159 ± 53
(68) |
141 ± 44
(77) |
119 ± 37
(66) |
126 ± 40
(60) |
125 ± 35 (56) | 112 ± 35
(51) |
| Loop C-I | C1 | 61-75 | 49 ± 5 | 49 ± 5 | 117 ± 47
(41) |
98 ± 39
(50) |
112 ± 51
(49) |
135 ± 57
(82) |
128 ± 51
(47) |
125 ± 59
(48) |
112 ± 55
(42) |
112 ± 56
(26) |
113 ± 46
(28) |
106 ± 43
(30) |
91 ± 40
(23) |
| Helix II | H2.1 | 76-87 | 65 ± 5 | 66 ± 6 | 96 ± 34
(26) |
89 ± 41
(22) |
74 ± 25
(14) |
100 ± 45
(29) |
90 ± 31
(37) |
108 ± 62
(16) |
99 ± 47
(20) |
90 ± 47
(11) |
74 ± 32
(14) |
97 ± 51
(8) |
80 ± 41
(9) |
| Helix II | H2.2 | 88-97 | 81 ± 4 | 82 ± 4 | 89 ± 34
(23) |
76 ± 27
(38) |
82 ± 30
(76) |
90 ± 36
(63) |
104 ± 39
(67) |
103 ± 45
(24) |
100 ± 40
(48) |
82 ± 48
(17) |
94 ± 41
(22) |
94 ± 31
(10) |
75 ± 30
(14) |
| Loop E-I | E1 | 98-108 | 97 ± 4 | 96 ± 3 | 106 ± 38
(118) |
103 ± 31
(146) |
119 ± 35
(161) |
132 ± 45
(175) |
142 ± 49
(130) |
152 ± 44
(85) |
136 ± 41
(114) |
101 ± 36
(70) |
103 ± 30
(59) |
117 ± 37
(67) |
99 ± 32
(57) |
| Helices III & IV, loops C-II & E-II | H3, H4, C2, E2 | 109-199 | 108 ± 2 | 107 ± 1 | 158 ± 53
(187) |
146 ± 37
(165) |
153 ± 40
(175) |
184 ± 53
(198) |
198 ± 54
(139) |
198 ± 50
(105) |
197 ± 52
(129) |
148 ± 42
(87) |
149 ± 40
(82) |
174 ± 42
(84) |
146 ± 41
(73) |
| Helix V & loop C-III | H5, C3 | 200-242 | 123 ± 5 | 121 ± 4 | 138 ± 45
(146) |
136 ± 40
(131) |
151 ± 47
(153) |
167 ± 53
(156) |
182 ± 58
(119) |
180 ± 57
(92) |
177 ± 50
(94) |
127 ± 41
(72) |
152 ± 48
(68) |
173 ± 44
(68) |
126 ± 42
(64) |
| Helix VI | H6.1 | 243-255 | 154 ± 4 | 138 ± 6 | 85 ± 34
(17) |
85 ± 31
(25) |
103 ± 42
(30) |
103 ± 34
(32) |
114 ± 41
(33) |
125 ± 27
(10) |
119 ± 34
(23) |
86 ± 20
(11) |
90 ± 41
(9) |
78 ± 12
(4) |
94 ± 43
(10) |
| Helix VI | H6.2 | 256-272 | 169 ± 6 | 170 ± 7 | 81 ± 34
(127) |
70 ± 35
(91) |
63 ± 20
(98) |
79 ± 35
(122) |
90 ± 47
(86) |
93 ± 47
(44) |
77 ± 38
(56) |
63 ± 14
(72) |
67 ± 33
(53) |
81 ± 31
(35) |
66 ± 37
(42) |
| Loop E-III | E3 | 273-285 | 195 ± 5 | 192 ± 6 | 79 ± 32
(30) |
69 ± 30
(35) |
65 ± 24
(52) |
85 ± 43
(48) |
76 ± 34
(44) |
92 ± 44
(34) |
81 ± 45
(45) |
64 ± 26
(14) |
73 ± 31
(12) |
77 ± 36
(19) |
92 ± 41
(15) |
| Helix VII | H7 | 286-309 | 208 ± 3 | 209 ± 3 | 99 ± 40
(46) |
83 ± 30
(49) |
81 ± 30
(75) |
94 ± 38
(78) |
97 ± 34
(71) |
93 ± 37
(46) |
96 ± 50
(58) |
91 ± 36
(40) |
81 ± 24
(39) |
80 ± 32
(32) |
77 ± 35
(25) |
| Helix 8 | H8 | 310-323 | 222 ± 6 | 223 ± 5 | 104 ± 44
(142) |
88 ± 37
(97) |
96 ± 37
(132) |
107 ± 44
(135) |
122 ± 47
(106) |
118 ± 43
(78) |
108 ± 42
(98) |
89 ± 37
(69) |
99 ± 34
(55) |
97 ± 45
(59) |
89 ± 41
(49) |
| C-terminal region | CT | 324-348 | 236 ± 6 | 236 ± 5 | 109 ± 47
(114) |
94 ±33
(109) |
120 ± 40
(117) |
119 ± 54
(115) |
133 ± 62
(73) |
139 ± 43
(46) |
128 ± 48
(75) |
103 ± 39
(55) |
113 ± 43
(35) |
107 ± 46
(51) |
101 ± 33
(40) |
a
Secondary structure(s) involved in the stable structural segment.
b
Name given for each stable structural segment.
c
Polypeptides that establish a structural segment. The first position in the polypeptide was determined from fitting force peaks to the WLC model.
d
Average number of amino acid residues (aa) stretched above the membrane obtained by fitting force peaks to the WLC model.
e
Average unfolding force calculated from force peaks. The number of F-D curves used in the calculations is shown in parentheses.
f
Data are those reported previously (9).