The chemical ionization mass spectra of free amino acids, their amides, methyl esters and Na-acetyl derivatives, using methane as reagent gas, are presented. The occurrence and fragmentation of ion-molecule reaction products are discussed. A preference for a 'head-to-tail' configuration of the association complex [2M + 11' is postulated to explain prominent fragmentation pathways of this complex. Interesting fragmentation pathways have been found with ornithine, arginine and ci trulline. I N T R O D U C T I O N IN CHEMICAL ionization (CI) mass spectrometry the molecules of a vaporized sample are ionized by a set of reagent ions in a series of ion-molecule reacti0ns.l to l5 The energy transferred by these reactions is lower than the energy of electron ionization (EI) and therefore fragmentation of the sample molecules is greatly decreased. For this reason CI mass spectrometry has been finding increasing use as a tool in the elucidation of the structures of a variety of organic compounds.16 to 28 Methane is often used as the reagent gas in CI mass spectrometry. The most abundant reacting species in the methane plasma are [CH,]+ (47 %), [C2H5]+ (41 %) and [C,H,]+ (6%). All three ionic species transfer groups to the sample molecules producing [M + HI+, [M + C,H,]+ and [M + C,H,]+ ions, respectively, (where M is the molecular weight of the compound under investigation). Initially, these 'adduct ions' appear to confuse the mass spectrum, but actually they have diagnostic value in the determination of M. In addition to the adduct ions, [2M + l]+ ionsfhave been found in the CI mass spectra of and alcohols,14 using isobutane as the reagent gas. Additionally [2M]+ ions were found with benzene.'In the framework of our investigations of oligopeptides we needed to obtain the CI mass spectra (with methane) of a series of natural amino acids, their amides, methyl esters and Nu-acetyl derivatives. We wish to report here on the occurrence and fragmentation of the [2M + 1]+ ion and other ion-molecule reaction products in the CI mass spectrometry of amino acids and their analogs. The CI mass spectra of free amino acids, using methane as the reagent gas, has been reported for ions with a mass equal to, or less than, [M + l]+ only.2f RESULTS FRAGMENTATION OF ION-MOLECULEThe CI mass spectra of the compounds studied are presented in Tables 1 to 4.

The primary sequence of the small cysteine-rich protein (EnvA) of Chlamydia psittaci 6BC has been shown to possess a potential lipid modification/signal peptidase 11-processing site, and the mature protein was labeled by a [3H]palmitic acid precursor. We further characterized the mature EnvA, showing that it lacks the N-terminal methionine of the primary peptide, is hydrophobic despite a peptide sequence that is predicted to be hydrophilic, and appears to be lipid modified at an N-terminal cysteine in a manner analogous to that of murein lipoproteins of gram-negative bacteria. We also report the fatty acid content of the small cysteine-rich proteins of C. psitaci and Chlamydia trachomatis L2 as determined by combined gas chromatography-mass spectrometry.Chlamydiae are obligate intracellular bacteria which possess a gram-negative cell envelope that appears to lack peptidoglycan (3,8). The genes encoding three envelope proteins, the major outer membrane protein and the large and small cysteine-rich proteins (CRPs), have been cloned and sequenced from several strains of chlamydiae, including Chlamydia psittaci 6BC (6, 7). In the nondividing, infectious, elementary body form of chlamydiae, the CRPs and the major outer membrane protein form a disulfide cross-linked supramolecular complex, which may be the functional equivalent of peptidoglycan (11,13,14,21). The major outer membrane protein is not cross-linked, and the CRPs are not made in the logarithmically dividing reticulate body form of chlamydiae (11,13,14,21).The small CRPs of Chlamydia trachomatis (Omp3) and C. psittaci (EnvA) appear to be lipoproteins: the primary sequences of Omp3 and EnvA contain potential lipid modification/signal peptidase II recognition sites (1, 7), and the C. psittaci small CRP is labeled from a [3H]palmitic acid precursor (7). The present study was undertaken to further characterize the small CRPs of chlamydiae. We have determined the fatty acid content of EnvA of C. psittaci and the small CRP of C. trachomatis, and we present evidence that EnvA is lipid modified at a cysteine residue in a manner similar to that of the murein lipoprotein of gram-negative bacteria.MATERIALS AND METHODS Purification of EnvA. Sodium dodecyl sulfate (SDS)-insoluble envelope protein complexes containing EnvA were prepared from Renografin-purified elementary bodies of C. psittaci 6BC and C. trachomatis LGV434 serotype L2 as described previously (7), except that noncovalently associated lipids were removed from the insoluble complexes by five extractions with 20-ml aliquots of methanol-chloroform-water (10:5:4 [vol/vol] (7) and protein A-Sepharose CL-48 (Sigma Chemical Co., St. Louis, Mo.). EnvA for combined gas chromatography-mass spectrometry (GC-MS) was separated from other proteins in chloroform-methanol-extracted envelope protein complexes by SDSpolyacrylamide gel electrophoresis (PAGE) (17) by using a step gradient gel consisting of 1 cm of 10% acrylamide and 15 cm of 15% acrylamide. The EnvA, with a mass of between 15 and 6 kDa, was excised and elut...

This study was designed to determine if opioids were detectable in cerebrospinal fluid (CSF) and if these concentrations were altered by hemorrhagic hypotension. This study was further designed to determine the effects of topically administered opioids on pial arteriolar diameter during normotension and hypotension. Closed cranial windows were used to determine pial arteriolar diameter. Periarachnoid cortical and cisterna magna CSF was collected from piglets during normotension and hypotension (systemic arterial pressure decreased from 63 +/- 1 to 33 +/- 1 mm Hg). Opioid profiles were assessed qualitatively by radioreceptor assay, and individual opioids were measured quantitatively by radioimmunoassay. Periarachnoid cortical and cisterna magna CSF methionine enkephalin-, leucine enkephalin-, dynorphin-, and beta-endorphin-like receptor active values all were increased by hypotension. When quantified by radioimmunoassay, periarachnoid cortical CSF values for methionine enkephalin-like immunoreactivity were 1,167 +/- 58 and 2,975 +/- 139 pg/ml for normotension and hypotension, respectively. Periarachnoid cortical CSF radioimmunoassay values for dynorphin-like immunoreactivity were 15 +/- 2 and 28 +/- 2 pg/ml for normotension and hypotension, respectively. When applied topically to the cortical surface, synthetic methionine enkephalin increased pial arteriolar diameter (134 +/- 4, 158 +/- 4, and 163 +/- 4 microns for control, 574 pg/ml [10(-10) M], and 5,740 pg/ml [10(-9) M], respectively). Similarly, topical synthetic leucine enkephalin and dynorphin elicited pial arteriolar dilation. However, beta-endorphin produced arteriolar constriction. Hypotension attenuated methionine and leucine enkephalin-induced dilation and reversed dynorphin-induced dilation to concentration-dependent constriction. beta-Endorphin-induced constriction was not changed by hypotension. Therefore, opioids could contribute to the control of the cerebral circulation during hypotension.

SUMMARY Two antihypertensive lipids can be extracted from fresh renal medulla. One is polar (the antihypertensive polar renomedullary lipid, or APRL) and the other is nonpolar (the antihypertensive neutral renomedullary lipid, or ANRL). APRL and ANRL differ in their biologic activities: APRL in bolus intravenous injections causes a very rapid decline in the arterial pressure (AP) while ANRL, after a lag of 2 minutes, causes a slower decline in AP. APRL increases heart rate and sympathetic activity. ANRL decreases heart rate and sympathetic activity. ANRL appears to convert to APRL, under certain in vitro circumstances, suggesting that the structure of the two molecules is related. ANRL and APRL appear in the renal venous effluent after unclipping; biologically, ANRL seems dominant. The renal venous effluent of the undipped isolated kidney lowers the HR and sympathetic activity of the normal rat. Unclipping degranulates the renomedullary interstitial cells (RIC). The antihypertensive effect of unclipping appears due to the secretion of ANRL and APRL by the kidney. It is concluded that ANRL seems to be the antihypertensive hormone of the RIC. been derived from fresh renal medulla. One is termed the "antihypertensive polar renomedullary lipid," or APRL, and the other, the "antihypertensive neutral renomedullary lipid," or ANRL.

1-0-alkyl ethers of phosphatidylcholine having an acetoyl in the second position were derived from fresh renal tissue. The main ether so derived had a 16:0 chain. The C16:0 alkyl ether was synthesized de novo. The renally derived and the synthetic ether exerted a similar and powerful antihypertensive action in hypertensive rabbits when given orally in divided doses. This action was prolonged, requiring more than 60 hours after the last input of the compound for recovery of the arterial pressure. As these ethers exerted their antihypertensive action, there was no evidence of adverse effects. Noteworthy was the failure of these depressor compounds to cause renin release. Diuresis-kaliuresis did not occur. A suggestion of sodium retention was noted.