- Email: [email protected]
On ternary complex formation between protein, metal ion, and a ligand
2454
Notes
RESULTS Results obtained from the series of reactions are illustrated in Table 1. Nielson and CranfordUT] reported a 36 per cent, yield. Our average of 32.1 per cent for four runs confirms the efficiency of this method. Table 1. Effect of metal halides on (PNCI2)3 yield Reaction No.
Metal halide
1 2 3 4 5 6 7 8 9 10 11 12 13 14
none none none none CoClz CuC12 HgCI2 LaCI3 MnCi~ MoCI5 NdCla NiCI~ PbCi2 VOCI2
Moles (× 104)
4-30 4.30 4.42 4.33 4.32 4.32 4.28 4.32 4.30 4.32
Wt. (g)
(PNCIz)3 obtained
Yield (%)
0.0558 0.0578 0.1201 0.1060 0.0544 0.1180 0-1072 0-0560 0.1196 0-0680
1.74 1.50 1.56 1.63 1.0 0.61 0.61 0-57 2.0 2.50 0.55 0.95 0.63 0.72
34.7 29.9 31.1 32.5* 20.0 12.2 12.4 11"4 39.9 50.0 11.0 19.0 12.6 14.4
(g)
*Av. -- 32.1. Results of previous workers show that the reaction rate is increased by the addition of COCI2, CuCl2 and MnCIv Our work indicates that, in some cases, this rate increase does not necessarily mean a trimer yield increase. Trimer yield was significantly reduced by CoCI~, CuCI2, HgCIv LaCls, NdCla, NiCI2, PbCI~ and VOC12. The slight increase in trimer yield in the presence of MnCI2 can be considered significant since other transition metals in the same period caused lower yields. The catalytic effect of MoCI5 is unquestionable for production of trimer. Work is continuing with this catalyst. The University o f Southwestern Louisiana, Lafayette, La. 70501 U.S.A.
J. inorg, nucl. Chem., 1970, Vol. 32, pp. 2454 to 2458.
R. W . J E N K I N S S. L A N O U X
Pergamon Press. Printed in Great Britain
On ternary complex formation between protein, metal ion, and a Hgand (First received 9 June 1969; in revised form I October 1969) THE proteins not only react with simple metal ions [ 1-5], but are also known to react with metal 1. 2. 3. 4. 5.
I. M. Klotz and H. G. Curme,J.Am. chem. Soc. 70, 939 (1948). C. Tanford, J. Am. chem. Soc. 73, 2066 (1951 ). H. P. Saroffand H. J. Mark, J . A m . chem. Soc. 75, 1420 (1953). M. S. N. Rao and H. Lal, J. Am. chem. Soc. 80, 3222 (1958). W. U. Malik and M. Muzaffaruddin,J. electroanal. Chem. 7, 214 (1963).
Notes
2455
Z +
~z~_
+
z~_
0
~Z +
Z Z ,t, +
~=x
0
+ II .4
[":".
Z I' 0
..~+
x o II
:fl - o,..4 ~ • +
~x Z
2456
Notes
,~+
~r., (.,)
0
+
~
°
+
Z 0
-H
~r.
~+ II ,4
~Z_.x [,-, I'
,h
0
x
g
~
+
~Zx
Notes
2457
complexes [6, 7]. The latter type of reaction is met with in some biological processes [8-10]. This communication is on the reactions of transfusion gelatin[I 1-12], a well eharacterised fibrillar protein used as a plasma expander (mol. wt. 75,000), with triethylenediamine nickel(lI) chloride and hexammine cobalt(ll I) chloride, investigated quantitatively by a polarographic method [ 13]. EXPERIMENTAL Transfusion gelatin (T.G.) was obtained through the courtesy of Director, N.C.L., Poona (India). Chemicals used were A.R. grade. Nickel [ 14] and cobalt [ ! 5] complexes were prepared in the laboratory. Measurements were carried out at pH 5-5 and 7.5 respectively in sodium acetate-acetic acid and potassium dihydrogen orthophosphate-sodium hydroxide buffers; 0.005% methyl red was used as the maxima suppressor. Polarograms were recorded with varying concentration of nickel and cobalt complexes in the presence and absence of fixed concentration (8 x 10-SM) of T.G. RESULTS AND DISCUSSION The binding data of metal complexes with proteins were calculated by Tanford's [ 13] method and shown in Tables 1 and 2. The values of the intrinsic a~sociation constant K calculated from Scatchard equation [16] are given in Table 3. Table 3. Values of log K at pH 5.5 with transfusion gelatin Metal ions and corresponding complex ions
Co 2+
Co(NHa)63+
Ni 2+
Ni(C~H4N2H4)3 ~+
log K
2.0
2.1
1.8
1.7
A comparison of the log K values of nickel [ 17] and cobalt [ 17] with those of their corresponding complexes for the binding to T.G. would reveal that complexation does not affect the original binding of these metals to the protein since logK values are approximately the same in both cases. In other words it may be said that ammonia and ethylenediamine, which are apparently unreactive with proteins get indirectly bound to the protein through Co and Ni. Gurd[8] has similarly found that giycine which has insignificant binding with serum albumin, after being complexed with zinc, is bound significantly. A comparison of the binding data (Tables 1 and 2) would further reveal that the cobalt complex shows greater binding than the nickel complex. Moreover, the binding is electrostatic in nature since the coordination valencies in both the complexes are already saturated. The values of the intrinsic association constants would suggest that the bonds are weak and that a similar situation should exist with respect to enzyme-substrate reactions. 6. E. A. Bouman, Sbornik Nauch and T. Vinaitsk, Referat. Zh. Khim., Biol. Khim. Abstr. No. 9626 (1958). 7. R'einosuke Hara, Bull. chem. Soc. Japan 22, 109 (1949). 8. B. G. Malmstrom, Archs Biochem. Biophys. 46, 345 (1953). 9. I. M. Klotz and W. C. Loh Ming, J. Am. chem. Soc. 76, 805 (1954). 10. T. R. Hughes and I. M. Klotz, J. A m. chem. Soc. 78, 2109 (1956). 11. S. L. Kalra, G. Singh and M. Ram, lndianJ, med. Res. 46, 171 (1958). 12. W. U. Malik and Salahuddin,J. electroanal. Chem. 6, 68 (1963). 13. C. Tanford, J. A m. chem. Soc. 73, 2066 (1951). 14. H. M. State, Inorganic Synthesis (Edited by E. G. Rochow), Voi. 6, p. 200. McGraw-Hill, New York (1960). 15. J. Bjerrum and J. P. McReynolds, Inorganic Synthesis (Edited by W. C. Fernelius), Vol. 2, p. 200. McGraw-Hill, New York (1960). 16. (3. Scatchard,Ann. N . Y . A c a d . Sci. $1,660 (1949). 17. S. K. Agarwal, Ph.D. Thesis, University of Roorkee, Roorkee, India (1966). 18. F. R. N. Gurd Ion Transport Across Membrane, (Edited by H. T. Clarke), p. 246, Academic Press, New York (1954).
2458
Notes
The values of AG (change in free energy) computed from the equation AG - - - - R T Ink come out to be -2814 cal/mole and -2318 cal/mole respectively at 25°C for the binding of the cobalt(Ill) and nickel(ll) complexes to T.G.. These values aga/n lend support to the view that the bond between complex ion and protein arises from electrostatic forces. It may be noted that the binding is higher at pH 7.5. Due to the electrostatic nature of the interaction, there exists little possibility of binding to the imidazole group. It may be concluded that somehow more carboxyl groups are made available for binding the complexes. Klotz[9] has also reported an increase in the binding of a metal-dye complex to proteins with increase in pH. These results can be used to explain the mechanism of metal activated enzyme-substrate reaction. The ligand, metal ion and protein can be taken as prototypes of the substrate, metal ion and enzyme, respectively and the formation of a ternary complex, with the metal acting as a bridge between enzyme and substrate can be visualized.
Department of Chemistry University of Roorkee Roorkee India
W A H I D U. M A L I K S. M A R G H O O B A S H R A F
J. inorg,nucl.Chem.. 1970,Vol.32, pp. 2458to 246I. PergamonPress. Printedin Great Britain
Spectroscopic studies on some
polyhalideions
(Received 22 December 1969) THE PREPARATION of polyhalide ions, usually simple stoichiometric preparations in organic solvents have been reported by several authors [1-4]. The low frequency vibrational spectra, particularly of the triiodide ion has also been the subject of a number of investigations (solid and solution i.r. and solution Raman) [5-8]. We report here the solid state i.r. and Raman spectra of compounds containing the ions I3-, Is-, 17-, 19-, I4C1-, 12Br-. In all the compounds R4Nia (R = Me, Et, Pr n) the solid state Raman spectra show a strong band at 104-108 cm -1 which is assigned to ~t of 13-. This is in accord with previously published solution spectral5]. In the far i.r. ~s and ~'2 are observed at approximately 130 cm -I and 70 cm -~ respectively (Table 1). The alkali metal triiodides, known to be ionic by X-ray structural studies have low frequency vibrational spectra consistent with the presence of I3-[5]. There appears however to be no previous report of the far i.r. spectrum of thallium triiodide. In our spectrum of thallium triiodide there is a strong band at 136 cm -t. This is more likely to be v3 of 13- than z,3 of a molecular Tlls(D3h). In the latter case 1,3 would be expected at a higher frequency than the assymmetric TI-I stretching mode in [Tllc](observed at 152 cm -j see Table 1). Our spectra therefore support X-ray studies which show isomorphism between TII3 and Cs1319], and also vapour pressure measurements on metal triiodides which suggest that TII3 is ionic [ 10]. The solid state vibrational spectra of R4NI5 (R = Me, Et, Pr n) are reported in Table I. Solution phase spectra could not be examined due to disproportionation of the 15- ion in solution. A simple F. D. Chataway and G. Hoyle, J. chem. Soc. 654 (1923). H.W. Cremer and D. R. Duncan, J. chem. Soc. 181 (1933). A. I. Popov and R. E. Buckels, Inorganic Syntheses Vol. 5, p. 167. Y. Yagi and A. 1. Popov, J. inorg, nucl. Chem. 29, 2223 (I 967). A . G . Maki and R. Fourneris, Spectrochim..4cta 23A, 867 (1967). S. G. W. Girm and J. L. Wood, Chem. Comm. 262 (1965). S. G. W. Ginn andJ. L. Wood, Trans. Faraday Soc. 62, 777 (1966). G . C . Hayward and P. J. Hendra, Spectrochim. Acta 2,3A, 2309 (1967). 9. A. C. Hazell, Acta crystaUogr. 16, 71 (1963). 10. A. G, Sharpe, J. chem. Soc. 2165 (1952). 1. 2. 3. 4. 5. 6. 7. 8.
Notes
RESULTS Results obtained from the series of reactions are illustrated in Table 1. Nielson and CranfordUT] reported a 36 per cent, yield. Our average of 32.1 per cent for four runs confirms the efficiency of this method. Table 1. Effect of metal halides on (PNCI2)3 yield Reaction No.
Metal halide
1 2 3 4 5 6 7 8 9 10 11 12 13 14
none none none none CoClz CuC12 HgCI2 LaCI3 MnCi~ MoCI5 NdCla NiCI~ PbCi2 VOCI2
Moles (× 104)
4-30 4.30 4.42 4.33 4.32 4.32 4.28 4.32 4.30 4.32
Wt. (g)
(PNCIz)3 obtained
Yield (%)
0.0558 0.0578 0.1201 0.1060 0.0544 0.1180 0-1072 0-0560 0.1196 0-0680
1.74 1.50 1.56 1.63 1.0 0.61 0.61 0-57 2.0 2.50 0.55 0.95 0.63 0.72
34.7 29.9 31.1 32.5* 20.0 12.2 12.4 11"4 39.9 50.0 11.0 19.0 12.6 14.4
(g)
*Av. -- 32.1. Results of previous workers show that the reaction rate is increased by the addition of COCI2, CuCl2 and MnCIv Our work indicates that, in some cases, this rate increase does not necessarily mean a trimer yield increase. Trimer yield was significantly reduced by CoCI~, CuCI2, HgCIv LaCls, NdCla, NiCI2, PbCI~ and VOC12. The slight increase in trimer yield in the presence of MnCI2 can be considered significant since other transition metals in the same period caused lower yields. The catalytic effect of MoCI5 is unquestionable for production of trimer. Work is continuing with this catalyst. The University o f Southwestern Louisiana, Lafayette, La. 70501 U.S.A.
J. inorg, nucl. Chem., 1970, Vol. 32, pp. 2454 to 2458.
R. W . J E N K I N S S. L A N O U X
Pergamon Press. Printed in Great Britain
On ternary complex formation between protein, metal ion, and a Hgand (First received 9 June 1969; in revised form I October 1969) THE proteins not only react with simple metal ions [ 1-5], but are also known to react with metal 1. 2. 3. 4. 5.
I. M. Klotz and H. G. Curme,J.Am. chem. Soc. 70, 939 (1948). C. Tanford, J. Am. chem. Soc. 73, 2066 (1951 ). H. P. Saroffand H. J. Mark, J . A m . chem. Soc. 75, 1420 (1953). M. S. N. Rao and H. Lal, J. Am. chem. Soc. 80, 3222 (1958). W. U. Malik and M. Muzaffaruddin,J. electroanal. Chem. 7, 214 (1963).
Notes
2455
Z +
~z~_
+
z~_
0
~Z +
Z Z ,t, +
~=x
0
+ II .4
[":".
Z I' 0
..~+
x o II
:fl - o,..4 ~ • +
~x Z
2456
Notes
,~+
~r., (.,)
0
+
~
°
+
Z 0
-H
~r.
~+ II ,4
~Z_.x [,-, I'
,h
0
x
g
~
+
~Zx
Notes
2457
complexes [6, 7]. The latter type of reaction is met with in some biological processes [8-10]. This communication is on the reactions of transfusion gelatin[I 1-12], a well eharacterised fibrillar protein used as a plasma expander (mol. wt. 75,000), with triethylenediamine nickel(lI) chloride and hexammine cobalt(ll I) chloride, investigated quantitatively by a polarographic method [ 13]. EXPERIMENTAL Transfusion gelatin (T.G.) was obtained through the courtesy of Director, N.C.L., Poona (India). Chemicals used were A.R. grade. Nickel [ 14] and cobalt [ ! 5] complexes were prepared in the laboratory. Measurements were carried out at pH 5-5 and 7.5 respectively in sodium acetate-acetic acid and potassium dihydrogen orthophosphate-sodium hydroxide buffers; 0.005% methyl red was used as the maxima suppressor. Polarograms were recorded with varying concentration of nickel and cobalt complexes in the presence and absence of fixed concentration (8 x 10-SM) of T.G. RESULTS AND DISCUSSION The binding data of metal complexes with proteins were calculated by Tanford's [ 13] method and shown in Tables 1 and 2. The values of the intrinsic a~sociation constant K calculated from Scatchard equation [16] are given in Table 3. Table 3. Values of log K at pH 5.5 with transfusion gelatin Metal ions and corresponding complex ions
Co 2+
Co(NHa)63+
Ni 2+
Ni(C~H4N2H4)3 ~+
log K
2.0
2.1
1.8
1.7
A comparison of the log K values of nickel [ 17] and cobalt [ 17] with those of their corresponding complexes for the binding to T.G. would reveal that complexation does not affect the original binding of these metals to the protein since logK values are approximately the same in both cases. In other words it may be said that ammonia and ethylenediamine, which are apparently unreactive with proteins get indirectly bound to the protein through Co and Ni. Gurd[8] has similarly found that giycine which has insignificant binding with serum albumin, after being complexed with zinc, is bound significantly. A comparison of the binding data (Tables 1 and 2) would further reveal that the cobalt complex shows greater binding than the nickel complex. Moreover, the binding is electrostatic in nature since the coordination valencies in both the complexes are already saturated. The values of the intrinsic association constants would suggest that the bonds are weak and that a similar situation should exist with respect to enzyme-substrate reactions. 6. E. A. Bouman, Sbornik Nauch and T. Vinaitsk, Referat. Zh. Khim., Biol. Khim. Abstr. No. 9626 (1958). 7. R'einosuke Hara, Bull. chem. Soc. Japan 22, 109 (1949). 8. B. G. Malmstrom, Archs Biochem. Biophys. 46, 345 (1953). 9. I. M. Klotz and W. C. Loh Ming, J. Am. chem. Soc. 76, 805 (1954). 10. T. R. Hughes and I. M. Klotz, J. A m. chem. Soc. 78, 2109 (1956). 11. S. L. Kalra, G. Singh and M. Ram, lndianJ, med. Res. 46, 171 (1958). 12. W. U. Malik and Salahuddin,J. electroanal. Chem. 6, 68 (1963). 13. C. Tanford, J. A m. chem. Soc. 73, 2066 (1951). 14. H. M. State, Inorganic Synthesis (Edited by E. G. Rochow), Voi. 6, p. 200. McGraw-Hill, New York (1960). 15. J. Bjerrum and J. P. McReynolds, Inorganic Synthesis (Edited by W. C. Fernelius), Vol. 2, p. 200. McGraw-Hill, New York (1960). 16. (3. Scatchard,Ann. N . Y . A c a d . Sci. $1,660 (1949). 17. S. K. Agarwal, Ph.D. Thesis, University of Roorkee, Roorkee, India (1966). 18. F. R. N. Gurd Ion Transport Across Membrane, (Edited by H. T. Clarke), p. 246, Academic Press, New York (1954).
2458
Notes
The values of AG (change in free energy) computed from the equation AG - - - - R T Ink come out to be -2814 cal/mole and -2318 cal/mole respectively at 25°C for the binding of the cobalt(Ill) and nickel(ll) complexes to T.G.. These values aga/n lend support to the view that the bond between complex ion and protein arises from electrostatic forces. It may be noted that the binding is higher at pH 7.5. Due to the electrostatic nature of the interaction, there exists little possibility of binding to the imidazole group. It may be concluded that somehow more carboxyl groups are made available for binding the complexes. Klotz[9] has also reported an increase in the binding of a metal-dye complex to proteins with increase in pH. These results can be used to explain the mechanism of metal activated enzyme-substrate reaction. The ligand, metal ion and protein can be taken as prototypes of the substrate, metal ion and enzyme, respectively and the formation of a ternary complex, with the metal acting as a bridge between enzyme and substrate can be visualized.
Department of Chemistry University of Roorkee Roorkee India
W A H I D U. M A L I K S. M A R G H O O B A S H R A F
J. inorg,nucl.Chem.. 1970,Vol.32, pp. 2458to 246I. PergamonPress. Printedin Great Britain
Spectroscopic studies on some
polyhalideions
(Received 22 December 1969) THE PREPARATION of polyhalide ions, usually simple stoichiometric preparations in organic solvents have been reported by several authors [1-4]. The low frequency vibrational spectra, particularly of the triiodide ion has also been the subject of a number of investigations (solid and solution i.r. and solution Raman) [5-8]. We report here the solid state i.r. and Raman spectra of compounds containing the ions I3-, Is-, 17-, 19-, I4C1-, 12Br-. In all the compounds R4Nia (R = Me, Et, Pr n) the solid state Raman spectra show a strong band at 104-108 cm -1 which is assigned to ~t of 13-. This is in accord with previously published solution spectral5]. In the far i.r. ~s and ~'2 are observed at approximately 130 cm -I and 70 cm -~ respectively (Table 1). The alkali metal triiodides, known to be ionic by X-ray structural studies have low frequency vibrational spectra consistent with the presence of I3-[5]. There appears however to be no previous report of the far i.r. spectrum of thallium triiodide. In our spectrum of thallium triiodide there is a strong band at 136 cm -t. This is more likely to be v3 of 13- than z,3 of a molecular Tlls(D3h). In the latter case 1,3 would be expected at a higher frequency than the assymmetric TI-I stretching mode in [Tllc](observed at 152 cm -j see Table 1). Our spectra therefore support X-ray studies which show isomorphism between TII3 and Cs1319], and also vapour pressure measurements on metal triiodides which suggest that TII3 is ionic [ 10]. The solid state vibrational spectra of R4NI5 (R = Me, Et, Pr n) are reported in Table I. Solution phase spectra could not be examined due to disproportionation of the 15- ion in solution. A simple F. D. Chataway and G. Hoyle, J. chem. Soc. 654 (1923). H.W. Cremer and D. R. Duncan, J. chem. Soc. 181 (1933). A. I. Popov and R. E. Buckels, Inorganic Syntheses Vol. 5, p. 167. Y. Yagi and A. 1. Popov, J. inorg, nucl. Chem. 29, 2223 (I 967). A . G . Maki and R. Fourneris, Spectrochim..4cta 23A, 867 (1967). S. G. W. Girm and J. L. Wood, Chem. Comm. 262 (1965). S. G. W. Ginn andJ. L. Wood, Trans. Faraday Soc. 62, 777 (1966). G . C . Hayward and P. J. Hendra, Spectrochim. Acta 2,3A, 2309 (1967). 9. A. C. Hazell, Acta crystaUogr. 16, 71 (1963). 10. A. G, Sharpe, J. chem. Soc. 2165 (1952). 1. 2. 3. 4. 5. 6. 7. 8.