Human ␣ 2 -antiplasmin (␣ 2 AP), also known as ␣ 2 -plasmin inhibitor, is the major inhibitor of the proteolytic enzyme plasmin that digests fibrin. There are 2 N-terminal forms of ␣ 2 AP that circulate in human plasma: a 464-residue protein with Met as the N-terminus, Met-␣ 2 AP, and a 452-residue version with Asn as the N-terminus, Asn-␣ 2 AP. We have discovered and purified a proteinase from human plasma that cleaves the Pro12-Asn13 bond of Met-␣ 2 AP to yield Asn-␣ 2 AP and have named it antiplasmin-cleaving enzyme (APCE). APCE is similar in primary structure and catalytic properties to membranebound fibroblast activation protein/seprase for which a physiologic substrate has not been clearly defined. We found that Asn-␣ 2 AP becomes cross-linked to fibrin by activated factor XIII approximately 13 times faster than native Met-␣ 2 AP during clot formation and that clot lysis rates are slowed in direct proportion to the ratio of Asn-␣ 2 AP to Met-␣ 2 AP in human plasma. We conclude that APCE cleaves Met-␣ 2 AP to the derivative Asn-␣ 2 AP, which is more efficiently incorporated into fibrin and consequently makes it strikingly resistant to plasmin digestion. APCE may represent a new target for pharmacologic inhibition, since less generation and incorporation of Asn-␣ 2 AP could result in a more rapid removal of fibrin by plasmin during atherogenesis, thrombosis, and inflammatory states. IntroductionHuman ␣ 2 -antiplasmin (␣ 2 AP), also known as ␣ 2 -plasmin inhibitor, is the main inhibitor of plasmin. 1 Plasmin plays a critical role in fibrin proteolysis and tissue remodeling. The physiologic relevance of plasmin inhibition by ␣ 2 AP to blood clotting and fibrinolytic homeostasis is supported by the following observations: (1) the rate of free plasmin inactivation by circulating ␣ 2 AP is much faster than fibrin(ogen) digestion by plasmin, 2 thereby eliminating the possibility of a systemic lytic state and consequent bleeding; (2) ␣ 2 AP is cross-linked to forming fibrin by activated blood clotting factor XIII (FXIIIa) and inhibits plasmin-mediated lysis in direct proportion to the amount incorporated 3-5 ; and (3) patients with homozygous ␣ 2 AP deficiency manifest serious hemorrhagic tendencies, while heterozygotes tend to bleed only after major trauma or surgery. 6 Human ␣ 2 AP is synthesized primarily in the liver, and during circulation in plasma, the secreted precursive Met-␣ 2 AP form, a 464-residue protein having Met as the N-terminus, undergoes proteolytic cleavage between Pro12 and Asn13 to yield Asn-␣ 2 AP, a 452-residue version with Asn as the N-terminus. 7 Met-␣ 2 AP accounts for approximately 30% of circulating ␣ 2 AP, and Asn-␣ 2 AP, approximately 70%. 7,8 While 3-fold more Asn-␣ 2 AP than recombinant Met-␣ 2 AP was shown to cross-link to fibrin, 9 no data have been reported for native circulating Met-␣ 2 AP. Moreover, the effect of different ratios of the 2 ␣ 2 AP forms on clot lysis has not been reported. Finally, the enzyme responsible for converting Met-␣ 2 AP to Asn-␣ 2 AP has not been ident...

Eleven types of nuts and seeds were analyzed to determine their energy (326-733 mg), moisture (1.6-18.3 mg), carbohydrate (8.8-70.9 mg), protein (4.9-30.5 mg), lipid (2.5-69.8 mg), and ash (1.2-5.5 mg) contents per 100 g of sample. Energy content was highest in pine nuts (733 mg/100 g), carbohydrate level was highest in dried figs (70.9 mg/100 g) and protein was highest in peanuts (30.5 mg/100 g). The amino acid compositions of nuts and seeds were characterized by the dominance of hydrophobic (range = 1,348.6-10,284.6 mg), hydrophilic (range = 341.1-3,244.3 mg), acidic (range = 956.1-8,426.5 mg), and basic (range = 408.6-4,738.5 mg) amino acids. Monounsaturated fatty acids (MUFA) were highest in macadamia nuts (81.3%), whereas polyunsaturated fatty acids (PUFA) were highest in the walnuts (76.7%). Macadamia nuts did not contain any vitamin E, whereas sunflower seeds contained the highest level (60.3 mg/kg). Iron (Fe) content was highest in pumpkin seeds (95.85 ± 33.01 ppm), zinc (Zn) content was highest in pistachios (67.24 ± 30.25 ppm), copper (Cu) content was greatest in walnuts (25.45 ± 21.51 ppm), and lead (Pb) content was greatest in wheat nuts (25.49 ± 4.64 ppm), significantly (P < 0.05). In conclusion, current commercial nuts and seeds have no safety concerns, although further analysis of Pb contents is necessary to ensure safety.

Alpha2-antiplasmin (alpha2AP) is the primary inhibitor of plasmin, a proteinase that digests fibrin, the main component of blood clots. Two forms of alpha2AP circulate in human plasma: a 464-residue protein with methionine as the amino-terminus (Met-alpha2AP) and an N-terminally-shortened 452-residue form with asparagine as the amino-terminus (Asn-alpha2AP). Human plasma alpha2AP concentration is 1 micro M and consists of approximately 30% Met-alpha2AP and approximately 70% Asn-alpha2AP. The major form (Asn-alpha2AP) is rapidly crosslinked to fibrin during blood clotting by activated coagulation factor XIII and as a consequence, fibrin becomes more resistant to fibrinolysis. It is apparent that alpha2AP is important in modulating the effectiveness and persistence of fibrin with respect to its susceptibility to digestion and removal by plasmin. Hence, the physiologic role of alpha2AP suggests that it may be a useful target for developing more effective treatment of thrombotic diseases. Research on alpha2AP appears to be moving in two main directions: (1) efforts to use variant forms of alpha2AP to reduce bleeding secondary to thrombolytic therapy while not slowing thrombolysis; and (2) efforts to use variant forms to diminish the activity of alpha2AP as a plasmin inhibitor so that fibrinolysis becomes enhanced. Methods to accomplish these two goals mostly involve manipulation of defined functional domains within the molecular structure of alpha2AP, or inhibition of a newly described novel plasma proteinase, termed antiplasmin-cleaving enzyme, that generates the more favorable form of alpha2AP, Asn-alpha2AP, for crosslinking to fibrin. The antiplasmin-cleaving enzyme has similarity in primary structure and catalytic properties to fibroblast activation protein/seprase. This review summarizes recent studies that may hold promise for modulating alpha2AP activity and its interactions with certain proteins as new therapeutic strategies for preventing and treating thrombotic disorders.

Weanling male Sprague-Dawley rats were fed one of four diets that varied in Cu, Zn or Cd content. To the control diet (I) Cu, Zn and Cd were added at 10, 100 and 0 mg/kg diet, respectively. Diets II and III also contained 10 mg/kg of dietary Cu, except that Zn was elevated to 1000 mg/kg for diet II, or Cd was added at 10 mg/kg for diet III. Diet IV was deficient in Cu (less than 1 mg/kg) with Zn at 100 mg/kg and no added Cd. At wk 6 postweaning, half of the rats fed diets I and IV were injected once with Cd acetate (5 mg Cd/kg body weight). The immediate response to Cd injection was an increase in metallothionein accumulation (three- to fourfold) and in Cu,Zn superoxide dismutase (SOD) accumulation (1.2- to 1.5-fold) in liver. SOD was estimated in an ELISA. These responses were not influenced by a change in Cu status (I vs. IV). However, in functional assays, SOD enzymatic activity was about half that of the control values. In this regard, SOD appears to be given high priority with respect to the utilization of cellular Cu, i.e., a 10-fold reduction in hepatic Cu only resulted in a twofold reduction in SOD activity and the amount of apoenzyme remained at normal levels.

The aim of this study was to examine the effects of perilla oil as well as several vegetable oils, including flaxseed oil, canola oil, and rice bran oil on plasma levels of cardioprotective (n-3) polyunsaturated fatty acids in mice by feeding each vegetable oil for a period of eight weeks. Concentrations of docosapentaenoic acid (DHA) and eicosapentaenoic acid (EPA), fish-based (n-3) polyunsaturated fatty acids, showed an increase in the plasma of mice fed perilla and flaxseed oils compared to those of mice in the control group (P < 0.05), whereas rice bran and canola oils did not alter plasma DPA and EPA concentrations. Arachidonic acid concentration was increased by feeding rice bran oil (P < 0.05), but not canola, flaxseed, or perilla oil. In addition, oleic acid, linoleic acid, and docosahexaenoic acid concentrations were altered by feeding dietary rice bran, canola, perilla, and flaxseed oils. Findings of this study showed that perilla oil, similar to flaxseed oil, is cardioprotective and could be used as an alternative to fish oil or even flaxseed oil in animal models.