The epitaxy-induced tetragonal strain in one monolayer of InAs buried in a GaAs(100) crystal is determined by measuring weak oscillations in X-ray reflectivity profiles. It is shown that the reflectivity of such heterostructure consists of a sinusoidal modulation of the usual rocking curve of a thick crystal. The oscillation period provides the distance of the buried layer from the crystal surface and the maximum positions in oscillations give the displacement induced by the buried layer. The vertical spacing between the In and As atom planes is found to be 1.64 +/- 0.02 Angstrom, which is consistent with an elastic behaviour.

The x-ray standing wave method is used to investigate some crystallographic features of the first stages of growth of ultrathin pseudomorphic MnTe(001) strained layers buried in CdTe on CdTe(001) substrates. Experiments with 004 and 113 reflecting planes show evidence of the presence of both MnTe clusters and diluted CdMnTe alloy.

The structure of an iron film, deposited at low temperature (50-degrees-C) upon a silicon (111) substrate, has been determined by means of X-ray Standing Wave experiments performed at LURE (Orsay, France). Experimental results are coherent with the model of an abrupt interface between the adsorbate and the surface: the first site of adsorption terminates the bulk silicon and a body-centred iron layer epitaxially grows on the substrate with a preferential growth orientation.

C I7H25N304.½H20,M r--344.4,monoclinic, B2, a = 18.299 (6), b = 18.781 (6), c= 5.917 (3)/~,, y= 110.65 (3) °, V= 1902.9 (10)A 3, Z = 4, CuKa, 2 = 1.54178/~, a = 0.73 mm -~, F(000) = 740, D x

C17H25N3O4.1/2H2O, Mr = 344.4, monoclinic, B2, a = 18.299 (6), b = 18.781 (6), c = 5.917 (3) A, gamma = 110.65 (3) degrees, V = 1902.9 (10) A3, Z = 4, Cu K alpha, lambda = 1.54178 A, mu = 0.73 mm-1, F(000) = 740, D chi = 1.202 Mg m-3, room temperature, final R = 0.048 and wR = 0.048 for all (1470) reflections. The molecules are stacked in layers along the alpha axis. There are five intermolecular hydrogen bonds.

C21H34N30+.CI -, Mr = 444.0,orthorhombic, P212121, a=26.074(5),b= 17.591 (4), c =5.224(2) A, V= 2396.1(10)A 3, Z=4, CuK~ 2=1.5418A, p=1.71mm -~, F(000)=952, D x= 1.231 Mg m -3, room temperature, final R = 0.080 and wR =0.070 for 2439 reflections [ (sin 0)/2 > 0.03 A-q.The peptide groups are planar; torsion angles (-101 and -88 °) indicate a roughly helical structure.The peptide bonds have a trans conformation.The crystal structure is stabilized by a network of hydrogen bonds.Tableau 1. Coordonn&s atomiques fractionnaires (x 104) avec leurs &arts-type entre parenth&es et facteurs d'agitation thermique dquivalents Introduction.

C21H34N3O5+.Cl-, Mr = 444.0, orthorhombic, P2(1)2(1)2(1), a = 26.074 (5), b = 17.591 (4), c = 5.224 (2) A, V = 2396.1 (10) A3, Z = 4, Cu K alpha, lambda = 1.5418 A, mu = 1.71 mm-1, F(000) = 952, D chi = 1.231 Mg m-3, room temperature, final R = 0.080 and wR = 0.070 for 2439 reflections [(sin theta)/lambda greater than 0.03 A-1]. The peptide groups are planar; torsion angles (-101 and -88 degrees) indicate a roughly helical structure. The peptide bonds have a trans conformation. The crystal structure is stabilized by a network of hydrogen bonds.

Some tripeptides obtained by enzymic digestion of caseins possess immunomodulating properties. In order to correlate activity and structure, X-ray analysis has been applied to two of them Leu-Leu-Tyr and Gly-Leu-Phe.

Correction of formulas (34), (37) and (38) of Agarwal's fast Fourier transform least-squares algorithm [Acta Cryst. (1978), A34, 791-809].

In the general case where there is only one molecule in the asymmetric unit, and in the absence of non-crystallographic symmetry, molecular-replacement (MR) techniques can be used to solve an unknown crystal structure from a closely related known molecular model. The procedure comprises two stages in order to find (i) the orientation of the model in the crystal, and (ii) the position of the well oriented model relative to the crystallographic symmetry elements. The most widely used rotation function R(θ) [Rossmann & Blow (1962). Acta Cryst. 15, 24-31], for stage (i), correlates the rotated central portion U of the Patterson function of the observed crystal with the calculated Patterson function of the proposed model. The calculation of the Patterson function of the model is performed in an arbitrary cell of sufficient size to prevent the overlap of intramolecular vectors from adjacent origins. Tollin & Rossmann [Acta Cryst. (1966), 21, 872-876] have proposed a criterion for the choice of the cell; this criterion is in fact sufficient but not necessary: after a discussion on the shape and the size of U, it is shown in this paper that the volume of the cell can be generally halved for the very same resulting map and, as a consequence, the computing time is also halved. Moreover, the size of the cell, even over-reduced, has a relatively weak influence on the ultimate conclusion of the MR calculation.

The structure of the high-temperature orthorhombic form of hen egg-white lysozyme has been determined at 2.0 A resolution. Initial images of the molecule were obtained at 6.0 A resolution both by double isomorphous replacement and by molecular replacement with use of the known structure of the room-temperature tetragonal lysozyme. The initial model thus obtained (R = 0.52 at 6.0 A) was refined first as a rigid body at 6.0 A and then by restrained least squares at 2.5 A and later at 2.0 A resolution. The final model (R = 0.23 at 2.0 A) was compared with that of the tetragonal form: the structures are very similar with a root mean square difference in superimposed alpha-carbon coordinates of 0.46 A. There are, however, differences which are caused by a crystal contact involving the upper part of this active site in the high-temperature orthorhombic form. Because of this, residues Trp 62 and Pro 70 are much better ordered than in the tetragonal form, where they are exposed to solvent. These differences can partly explain the difficulty of inhibitor-binding in high-temperature orthorhombic crystals, but do not seem to reflect the particular behaviour of lysozyme in solution at high temperature.

The structure of the symmetrical dimer of oxidized rabbit Uteroglobin, as determined from the crystal form in space group C2221, has been used as a model to determine the general parameters of this protein in two other crystal forms; namely, a symmetrical dimer in P21212 and an asymmetrical dimer in P21 with non-crystallographic symmetry approaching P21212. Independently, the structure in P21212 was solved by multiple isomorphous replacement.

A new translation function T(t) is defined, whose main peak is expected to give directly the absolute position t = t o of a known molecular configuration (the isostructural model) of known orientation in an unknown crystal structure.T(t) combines all required information: crystal symmetry, molecular steric properties of the model and experimental data (observed structure factors F o) leading to more reliable results: T(t) = TO(t)/O(t), where TO(t) measures the degree of agreement between F o and Fc(0, while O(t) is a function measuring intermolecular overlap.TO and O can both be computed efficiently by the possibility of their expansion in Fourier series, and the use of FFT.A theoretical study followed by application to a simple synthetic structure cast light upon ambiguities and failures [e.g.

The molecular replacement method consists of the three consecutive stages : (1) determination of the orientation of the molecule in the crystal, (2) determination of the position of the molecule and (3) solution of the phase problem.The problem in the first stage was solved almost satisfactorily by using the rotation function first developed by Rossmann and Blow and recently improved by Crowther.In the second stage, the problem was not always solved satisfactorily because of several theoretical and/or computational drawbacks inherent to the translation function.Lack of efficient translation functions of universal applicability prevented the po-tentially much more powerful molecular replacement method from being popular in the structure determinations of macromolecules.A case of a known model structure is discussed, considering the origins of inefficacy of the translation functions proposed so far, and a new powerful translation function which is highly efficient in computation is proposed.

FEBS LettersVolume 116, Issue 1 p. 48-50 Full-length articleFree Access Contribution to the study in solution and solid state of the rabbit aldolase temperature dependence P. Jollès, P. Jollès Laboratoire des Protéines, Universités de Paris V et VI, 45 rue des Saints-Pères, F-75270 Paris Cedex 06, FranceSearch for more papers by this authorJ. Berthou, J. Berthou Laboratoire de Minéralogie-Cristallographie associé au CNRS, Université de Paris VI, 4 pl. Jussieu, F-75230 Paris Cedex 05, FranceSearch for more papers by this authorA. Lifchitz, A. Lifchitz Laboratoire de Minéralogie-Cristallographie associé au CNRS, Université de Paris VI, 4 pl. Jussieu, F-75230 Paris Cedex 05, FranceSearch for more papers by this authorA. Clochard, A. Clochard Centre de Transfusion Sanguine des Armées ‘J. Julliard’, 1 rue Raoul Batany, F-92140 Clamart, FranceSearch for more papers by this authorJ. Saint-Blancard, J. Saint-Blancard Centre de Transfusion Sanguine des Armées ‘J. Julliard’, 1 rue Raoul Batany, F-92140 Clamart, FranceSearch for more papers by this author P. Jollès, P. Jollès Laboratoire des Protéines, Universités de Paris V et VI, 45 rue des Saints-Pères, F-75270 Paris Cedex 06, FranceSearch for more papers by this authorJ. Berthou, J. Berthou Laboratoire de Minéralogie-Cristallographie associé au CNRS, Université de Paris VI, 4 pl. Jussieu, F-75230 Paris Cedex 05, FranceSearch for more papers by this authorA. Lifchitz, A. Lifchitz Laboratoire de Minéralogie-Cristallographie associé au CNRS, Université de Paris VI, 4 pl. Jussieu, F-75230 Paris Cedex 05, FranceSearch for more papers by this authorA. Clochard, A. Clochard Centre de Transfusion Sanguine des Armées ‘J. Julliard’, 1 rue Raoul Batany, F-92140 Clamart, FranceSearch for more papers by this authorJ. Saint-Blancard, J. Saint-Blancard Centre de Transfusion Sanguine des Armées ‘J. Julliard’, 1 rue Raoul Batany, F-92140 Clamart, FranceSearch for more papers by this author First published: July 14, 1980 https://doi.org/10.1016/0014-5793(80)80526-6Citations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. References 1 P. Jollès, J. Berthou, FEBS Lett., 23, (1972), 21– 23. 2 P. Cozzonne, S.J. Opella, O. Jardetzky, J. Berthou, P. Jollès, Proc. Natl. Acad. Sci. USA, 72, (1975), 2095– 2098. 3 J. Saint-Blancard, J. Mazurier, M. Bournaud, J.-P. Maurel, J. Berthou, P. Jollès, Mol. Biol. Rep., 5, (1979), 165– 169. 4 J. Saint-Blancard, A. Clochard, P. Cozzone, J. Berthou, P. Jollès, Biochim. Biophys. Acta, 491, (1977), 354– 356. 5 R.R. Matheson, H.A. Scheraga, Biochemistry, 12, (1979), 2446– 2450. 6 P.L. Privalov, Adv. Prot. Chem., 33, (1979), 189– 192. 7 H.P. Wolf, F. Leuthardt, Helv. Chim. Acta, 40, (1957), 237– 246. 8 G. Beisenherz, H.J. Boltze, T. Bücher, R. Czok, K.H. Garbade, E. Meyer-Arendt, G. Pfleiderer, Z. Naturforsch., 8b, (1953), 555– 557. 9 P.A.M. Eagles, L.N. Johnson, M.A. Joynson, C.H. McMurray, H. Gutfreund, J. Mol. Biol., 45, (1969), 533– 544. 10 E.G. Heidner, B.H. Weber, D. Eisenberg, Science, 171, (1971), 677– 679. 11 L. Sawyer, J. Mol. Biol., 71, (1972), 503– 505. Citing Literature Volume116, Issue1July 14, 1980Pages 48-50 ReferencesRelatedInformation

FEBS LettersVolume 108, Issue 1 p. 10-12 Full-length articleFree Access On the binding of N-acetylglucosamine and chitobiose to hen lysozyme in the solid state at high temperature J. Berthou, J. Berthou Laboratoire de Minéralogie-Cristallographie associé au CNRS, Université de Paris VI, 4, place Jussieu, F-75230 Paris Cedex 05, FranceSearch for more papers by this authorA. Lifchitz, A. Lifchitz Laboratoire de Minéralogie-Cristallographie associé au CNRS, Université de Paris VI, 4, place Jussieu, F-75230 Paris Cedex 05, FranceSearch for more papers by this authorJ. Saint-Blancard, J. Saint-Blancard Centre de Transfusion sanguine des Armées 'J. Julliard', 1 rue Raoul Batany, F-92140 Clamart FranceSearch for more papers by this authorP. Jolles, P. Jolles Laboratoire des Protéines, Université de Paris V, 45 rue des Saints-Pères, F-75270 Paris Cedex 06, FranceSearch for more papers by this author J. Berthou, J. Berthou Laboratoire de Minéralogie-Cristallographie associé au CNRS, Université de Paris VI, 4, place Jussieu, F-75230 Paris Cedex 05, FranceSearch for more papers by this authorA. Lifchitz, A. Lifchitz Laboratoire de Minéralogie-Cristallographie associé au CNRS, Université de Paris VI, 4, place Jussieu, F-75230 Paris Cedex 05, FranceSearch for more papers by this authorJ. Saint-Blancard, J. Saint-Blancard Centre de Transfusion sanguine des Armées 'J. Julliard', 1 rue Raoul Batany, F-92140 Clamart FranceSearch for more papers by this authorP. Jolles, P. Jolles Laboratoire des Protéines, Université de Paris V, 45 rue des Saints-Pères, F-75270 Paris Cedex 06, FranceSearch for more papers by this author First published: December 01, 1979 https://doi.org/10.1016/0014-5793(79)81166-7Citations: 2 Address correspondence to Professor P. Jollès AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. References 1 P. Jollès, J. Berthou, FEBS Lett., 23, (1972), 21– 23. 2 J. Berthou, P. Jollès, Biochim. Biophys. Acta, 336, (1974), 222– 227. 3 P. Cozzone, S.J. Opella, O. Jardetzky, J. Berthou, P. Jollès, Proc. Natl. Acad. Sci. USA, 72, (1975), 2095– 2098. 4 J. Saint-Blancard, A. Clochard, P. Cozzone, J. Berthou, P. Jollès, Biochim. Biophys. Acta, 491, (1977), 354– 356. 5 P. Jollès, J. Saint-Blancard, M. Allary, J.-P. Périn, P. Cozzone, FEBS Lett., 55, (1975), 165– 167. 6 J. Saint-Blancard, J. Mazurier, M. Bournaud, J.-P. Maurel, J. Berthou, P. Jollès, Mol. Biol. Rep., 5, (1979), 165– 169. 7 J.A. Rupley, L. Butler, M. Gerring, F.J. Hartdegen, R. Pecoraro, Proc. Natl. Acad. Sci. USA, 56, (1967), 1088– 1092. 8 C.C.F. Blake, G.A. Mair, A.C.T. North, D.C. Phillips, U.R. Sarma, Nature, 196, (1962), 1173– 1176. 9 K.J. Palmer, M. Ballantyre, J.A. Galvin, J. Am. Chem. Soc., 70, (1948), 906– 910. 10 M. Wenzel, H.P. Lenk, E. Schutte, Z. Physiol. Chem., 327, (1967), 13– 20. 11 L.N. Johnson, D.C. Phillips, Nature, 206, (1965), 761– 762. 12 O.B. Ptitsyn, FEBS Lett., 93, (1978), 1– 4. 13 K. Hayashi, K. Hamaguchi, M. Funatsu, J. Biochem., 53, (1963), 374– 380. 14 C.C.F. Blake, L.N. Johnson, G.A. Mair, A.C.T. North, D.C. Phillips, V.R. Sarma, Proc. Roy. Soc. B, 167, (1967), 378– 388. 15 S.J. Perkins, L.N. Johnson, P.A. Machin, D.C. Phillips, Biochem. J., 181, (1979), 21– 36. 16 T. Imoto, L.N. Johnson, A.C.T. North, D.C. Phillips, J.A. Rupley, 3rd edn The Enzymes 7, (1972), 663– 868. 17 P.J. Artymuik, C.C.F. Blake, D.E.P. Grace, S.J. Oatley, D.C. Phillips, M.J.E. Sternberg, Nature, 280, (1979), 563– 568. 18 R. Huber, Nature, 280, (1979), 538– 539. Citing Literature Volume108, Issue1December 01, 1979Pages 10-12 ReferencesRelatedInformation

The crystal structure at room temperature (20 °C) of TBBA has been solved; this compound gives rise to several liquid-crystal forms at higher temperatures.A model for the disorder of the butyl side chains is proposed.This disorder is probably connected with the transition point at 113°C which leads to a smectic B form.The lattice parameters of the low-temperature crystalline form have been determined.At 20°C TBBA crystallizes in the monoclinic system, C2/c, Z = 8, with a = 53.2(+0.1),b = 5-75 (+0.005), c = 17.57(+0.003) /k,/~ = 115.47(_+0.05)°.MULTAN and a full-matrix least-squares refinement have been employed.Final R and R,,, valu'es are 0.133 and 0. 167 for the 4020 reflexions.The two butyl side chains have only been partially refined since disorder does not allow an accurate description.Plan 1 Plan 2 Plan 3 C(21) -0,022 C(7) -0,110 *C(15) 0,004 *C(1) --0,004 C(14) -0,084 *C(16) -0,015 *C(2) -0,000 *C(8) --0,020 *C(17) 0,012 *C(3) 0,002 *C(9) 0,013 *C(I 8) 0,002 *C(4) 0,001 *C(10) 0,006 * C(19) -0,013 *C(5) -0,006 *C(11) -0,017 *C(20) 0,010 *C(6) 0,008 *C(12) 0,009 *C(25) 0,110 N(1) -0,045 *C(l 3) 0,009 *N(2) 0,072 Plan 4 Plan 5 Plan 6 *C(4) -0,026 *C(l 1) 0,007 *C(I) 0,019 *N(I) 0,025 *C(14) -0,007 *C(21) -0,020 *C(7) 0,026 *N(2) -0,007 *C(22) -0,018 *C(8) -0,025 *C(15) 0,007 *C(23) 0,019 Plan 7 Angles entre les plans (o)The structure of a crystalline phase of TBBA is compared with the structure of the smectic B mesophase which appears on melting at 113 °C.In the crystal, molecules show some disorder, including large-amplitude motions of the terminal carbons and longitudinal displacements, and are arranged in layers.These characteristics are enhanced in the smectic B phase, the most important differences between the structures of the two phases arising from both the molecular conformation and the lateral packing of the molecules, which enable rotational jumps to occur.